Ok go to Control Panel via the Start menu, (if you have the classic look double click Network Connections). find your Wireless connection , right click on it and select properties. Scroll down the list and find "Internet Protocol (TCP/IP) and highlight it, now click Properties. Now click on "Use the following IP Address" and type in the first box 192.168.1.2 clcik in the Default Subnet Mask Box and 255.255.255.0 should appear automatically. Now click in the Default Gateway box and type 192.168.1.1, Hit Apply then ok.
Go into Internet Explorer and type
http://192.168.1.1 and press enter. You should then get your router page appear, and you can make the nessesary changes, then change the network card properties to automatically obtain an IP Address and DNS Server Addresses automatically.