Did you forget to log out of Facebook at your friend's house, did you accidentally click on something you shouldn't have, or has your account been hacked?
Their goal was to steal your password and other account credentials, and they may have succeeded.
If you're not sure about what it found, ask a friend who might.
I’m so sorry for taking this long to write you back. And the most fifth grade fear of all: will you be mad at me? One day, drowning in electronic apologies, it hit me: I have the curse of the e-Good Girl. But if you’re the kind of person who worries about disappointing others, who wants to be liked, who wants to do everything right, a mounting pile of email lights your Good Girl issues up like a Christmas tree.
I recommend Microsoft Security Essentials –it's free and gets the job done very well. If you have a Mac, try using the antivirus from Sophos.
After running the virus scan, clean out whatever the program detects.