You need the address of the router in your network so press the Windows key and R together. In the Run box that appears, type
cmd /k ipconfig /all
then press the Enter key.
A black form shows up with a list if detalis and you need what's written beside Default Gateway - something like 192.168.0.1. Take that information and put in the address bar of Internet Explorer or any other browser as though it was a web address.
When you get in, you'll need the login details and if they aren't printed on the box, you're in trouble. Try admin as the name and password as the password. You might get lucky.
The wireless details are probably listed under Security.