1. Connect DSL Modem to Wireless Router with Ethernet cable.
2. Connect Wireless Router to PC with second ethernet cable.
3. Type 192.168.0.1 (or whatever address is provided in the manual for your wireless router) into the 'address' bar on your browser (not the 'search' bar).
4. Log in to your wireless router using username and password as provided in the wireless router manual.
If this doesn't appear to work, i would suggest you switch off all three, then switch them back on in the following order: 1 - DSL modem. Wait 20 seconds. 2 - Wireless router. Wait for the lights to all come on and then they'll settle down. 3 - Switch your PC back on.
Then try to access your Wireless Router via the 192.168.0.1 address.