Start by reseting the router to factory defaults (if it has been used for another connection). Connect your pc via cable and aquire an address (should get one automatically from DHCP). Enter the router address in your brouser's addrss bar. This should give you the routers web page. If you dont't know what the address is, just check your network settings and use the "Default Gateway" address (that is your router). Enter the configuration using login and go to the WAN settings. Select your internet type (PPoE, PPoA or whatever you have at home) then enter the username and password you were given by your ISP. If you don't have them thn contact ISP for information. Apply the settings and you should then get an internet connection.
Otherwise you can use the "Connection Wizard" function if your router has it. The wizard will detect ISP settings (not username or password).