|If you don't know the WEP key to enter, you will find it either on a sticker attached to the router, or in the router's configuration utility which appears in your web browser. Open any web browser and type your router's IP address into the address bar, then press <Enter>.|
For most routers, the IP address for it's configuration utility is either http://192.168.1.1 or http://192.168.0.1
When you've got the router's configuration utility open, go into the wireless section and you'll see what the WEP or WPA key is for it. Write it down clearly on a sheet of paper, remembering that lower-case and upper-case letters must be written down exactly like that because a wireless key is case-sensitive.
On laptop, double-click the appropriate network to connect to and a box should appear where you enter the same WEP or WPA key that you got from the router configuration utility.