Setup is asking for WPA2 key..what is WPA2 and where can I find it?

This router does not use any type of PIN. You may be confused as the HP wireless networking setup may be asking for the "password", or WPA2 key that secures the wireless network. This must be entered before the router will accept the client and assign it a network IP address. The WPA2 key is stored in the router under the Wireless Settings Option. Unfortunately, if you don't know the key, going there won't help you as the key is not visible.

Network Key (WEP, WPA, WPA2 Encryption key)
To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router.
http://www.fixya.com/support/r5270415-network_password_network_address
For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :-
http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

The encryption key maybe incorrect.
Network Key (WEP, WPA, WPA2 Encryption key) To connect your computer to a wireless router, you click the Refresh network list, then Choose your wireless network and then click Connect to your secured Wireless Network, it will asks for a Network Key before allowing you to connect into your wireless network. This Network Key is either the WEP, or WPA or WPA2 Encryption key that is configured in the Wireless settings in the Router. The Passphrase is an alternate way to setup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrase or WPA or WPA2 key that was used to configure the Encryption key in the wireless router. http://www.fixya.com/support/r5270415-network_password_network_address For information on securing your wireless network, configuring the wireless router and configuring the wireless card in the laptop/computer, please click on this link and follow my instructions :- http://www.fixya.com/support/r3559128-wireless_router_security

Network Key (WEP, WPA, WPA2 Encryption key)To connectyour computer to a wireless router, you click the Refresh networklist, then Choose your wireless network and then click Connectto your secured Wireless Network, it will asks for a Network Keybefore allowing you to connect into your wireless network. This NetworkKey is either the WEP, or WPA or WPA2 Encryption key that is used toconfigure the Wireless Router. The Passphrase is an alternate way tosetup the Encryption key.
When you are requested for a Network Key, you can just enter the Passphrasethat was used to configure the Encryption key in the wireless router.http://www.fixya.com/support/r5270415-network_password_network_addressFor information on securing your wireless network,configuring the wireless router and configuring the wireless card in thelaptop/computer, please click on this link and follow my instructions :-http://www.fixya.com/support/r3559128-wireless_router_security

To setup your Brother MFC-7840W on a wireless network do the following:

Press Menu.

Scroll down to #5 LAN and hit OK

In the LAN submenu, scroll down to 2. WLAN and hit OK.

In the WLAN submenu select 2. Setup Wizard.
(The printer will search for the SSID of your network. If you are presented with multiple networks, select yours and hit OK.)

Depending whether you have setup a network key on your wireless network, you will have to choose the type of connection. Your options will be Open System, Shared key, and WPA/WPA2-PSK.

If you have a Shared Key or WPA/WPA2-PSK network, then you willhave to enter the key to connect. Open Key does not use a key to connect.

So for instance, if you selected WPA2-PSK you will then be asked to enter your passphrase key to connect to your wireless network.