Here is a link to a pdf file that has a lot of good information on facebook security. I encourage you to download and read it.

http://www.google.com/url?sa=t&rct=j&q=facebook%20security&source=web&cd=3&ved=0CIABEBYwAg&url=http%3A%2F%2Fwww.facebook.com%2Fsafety%2Fattachment%2FGuide%2520to%2520Facebook%2520Security.pdf&ei=qZmuT_71FumfiALmoKz6Aw&usg=AFQjCNHY0ZaXaKGnTu3yCOi2MVe0yTx5jA