I've got a rather newbish question.

I'm at my cousin's house and he has an unprotected wireless network. The wireless hub is a belkin Wireless G Router. I am wired into it. He connects to it wirelessly. I've tried setting up a home entwork through windows, and set up a wireless connection through windows (though im not conneted wirelessly). I've been googling for the past hour and a half without much success. His computer is a Mac and he tried setting it up on his, but it just made some new non-existent network, and after all attempts there is still nothing stopping anyone from connecting to the wireless. How can I protect it with WEP, or mac address filtering from my wired in PC? Thanks for your help AO