WEP is a security feature which can be enabled on wireless APs/routers.
Assuming your internet is going through a router you will need to logon to the routers configuration page.
right-click on your network connection (start->settings->network connections) and click on status. Then click the support tab and write down the default gateway IP.
Next, open IE or FireFox and type: http://192.168.1.1 or whatever your default gateway IP is.
Once connected to the router you will get a login page. If you do not know the username and password the following are typical default settings:
If none of these work, you may be prohibited from accessing this routers configuration settings; is this your router?
Once logged into the router go to the routers wireless settings page; there should be a link that says wireless settings or or something to that effect. Once here you will see WEP (if it is enabled) in a drop down box, and you will need to change the option from WEP to None.
Warning* this will disable wireless security on your router.
If you need more assistance, just post again and someone will get to you. Hope this helps.