I am not sure if I understand you well.
My Internet is a PPPoE broadband connection but I don't have a modem installed.
What do you mean ?
You have a Broadband/ADSL modem, but you didn't install any software for it ?
(It is probably not necessary.)
So, I assume you do have a modem. You connect your modem to the wall outlet with a telephone cable.
Then then modem is connected with LAN cable to one of your PC with two NICs, you make Internet Connection Sharing, and ten from the second NIC of that PC, you connect (again) with LAN cable, your second PC.
If it is an ADSL or Cable modem connected with LAN cable, please follow this steps.
First RESET your Edimax router and disconnect all LAN cables if connected.
Connect your PC (the one with one NIC) to one of the 4 LAN ports of your Router wit a LAN cable.
Open My Network Places and then View network connections, or go to Control Panel and open Network Connections.
Right-Click on your LAN adapter and choose Properties, then double-click on Internet Protocol (TCP/IP)
Set to 'Obtain IP address automatically' and 'Obtain DNS server addres automatically' (click OK). Now you are back to the previous window. Click and check (if it is not) 'Show icon notification when connected' and once again click OK.
After a fiew seconds you should get (near to the clock in the the right bottom of your desktop), a Network icon and a baloon message that your NIC is connected.
Right-click on the network icon and click STATUS, a window will open
and then click on SUPPORT tab.
You should see:
IP Addres: 192.168.2.100
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.2.1
Open your browser and type http://192.168.2.1
Now login as:
and password is: 1234 (default)
Click on GENERAL SETUP on Top-Left, and then on WAN (on the right side) and choose
Click on 'More configuration'
Type your User Name and Password you have from your ISP.
Now Click on APLY, and again APLY !
The Router will restart in 30 Sec, and your NIC will reconnect.
Now connect your Modem to a WAN port of your Router with LAN cable. (***)
if you've typed your User Name and Password correctly in PPPoE fields,
if everything is OK with the service from your provider,
you should now be on Internet.
If not, then please check your User Name and Password with your Internet Service Provider, and ask them if they can see your router.
Now, get to the PC with two NICs.
Go to Control Pannel, and go to Network Connections.
Right-click on one of your NICs and click 'Disable'.
Check the other NIC if 'Internet Protocol (TCP/IP)' settings are set to Obtain IP addres and DNS - Automatically, and 'Show icon notification when connected' and once again click OK.
Connect the (enabled) NIC with LAN cable to another port of your router.
The second PC should be on Internet, too.
If you (somehow) realy don't have a modem, but you have a cable only, follow the above instructions to the point (***) and connect the cable to the WAN port of your router.