I want security key of my router TP-LINK-740 - TP-LINK TL-WR740N Router

Some later model wireless routers have the Password(ie.Encryption key) and the SSID already configured in the wireless router andthis information is printed on a label on the bottom of the router.
These settings can be used to configure the wireless card and wireless adaptersin your computer/laptop.
If these settings do not suit you, then it can be changed to suit yourrequirements.
The encryption key secures your data and wireless connection from unauthorizedaccess.To configure the wireless settings in the router, connect a LAN cablefrom your computer to the wireless router, then open a Browser on your computerand enter the router's configuration IP address, then enter the admin login andpassword and then go to the wireless settings and configure the SSID andEncryption key.
The router's encryption key can be a Passphrase or the WEP or WPA or WPA2key.If you use the Passphrase method select either WEP or WPA or WPA2 togenerate the encryption key. You can enter the WEP or WPA or WPA2 key with 8 to63 ASCII characters or 64 Hex digits.
Most people use Passphrase which is easier to remember eg. I was born inJanuary 1988.
The strongest and latest security is WPA2, the weakest and oldest is WEP. Toconnect to your wireless router from the computer/laptop, configure thewireless card in your computer/laptop with the router's wireless settings ieSSID, plus the WPA or WPA2 encryption key. Then computer/laptops cancommunicate with your wireless router.http://www.fixya.com/support/r10267861-network_security_key