How to put a password on a wireless router

Hello, i have a wireless router. the model of the router is WRT54G
I just want to know how to make it password protected so that my neighbors cant access it at the click of a button, i have visted the linksys website, and they couldn’t tell me much All i know is, you have to do:
Open I.E. on your hardwired computer and in the address bar type 192.168.15.1, Linksys setup page would pops up�click on the wireless tab
then i dont know what to do.
can someone please help me. thank you.
Answer #1
WRT54G http://blogcritics.org/archives/2006/08/08/131947.php
http://answers.yahoo.com/question/index?qid=20061025163531AAnZl3O
http://forums.linksys.com/linksys/board/message?board.id=Wireless_Routers&message.id=3656
Answer #2
Answer #3
ahh this sucks, they all say different things
thanks for you’re help though.