Securing a wireless networks

[Calendros]

Ok, I'm not exactly the most tech savvy, despite my better judgement. I want to know an -easy- way to secure my information on a wireless network, so when I set up filesharing on my desktop and laptop, I don't want people to be able to access my network, and if they do, they can't do anything with my comps. I tried searching the forums, but nothing seems to fit what it is I'm really looking for. I'd prefer not to have to install alot of files, and I'd really only like a do-it-once-and-forget-about-it solution, if possible.
I'm currently on a linksys wireless, WAP11 router, if that helps any.

Any ideas? I'd greatly appreciate it.