Mac Forums

So I have a used Mac OS X and I can not get it connected to the internet. I also have never used a mac before so I completely confused. I called comcast for help and turns out they charge to have a laptop connected. So now I am stuck playing around with a laptop that I really have no idea how to use. When I click the "AirPort" icon at the top of the screen I see my network listed, but when I enter my password, it says "There was an error joing the AirPort network "XXXXXXX"". Any help would be greatly appreciated, please let me know if you need more info.