|From a command prompt type ipconfig. You router address is the Default Gateway. Probably something like 192.168.1.1|
Type that into the address bar of your browser. You will be prompted for a user name and password. You will need to get that from whoever set-up the router. Once you get into the router you will probably find that the WPA password is just a row of asterisks. In which case you will need to get that from whoever set-up the router.