Click on the "Profile" button, then click on the "Forum Profile Information" button to your left - there you'll see 3 choices: "Personalized Picture", "I have my own picture" or "I will upload my own picture".
If you have the picture you want to use on the computer you should choose "I will upload my own picture" and then simply search through your computer for the picture you want to use.
This thread should probably be on the "Forum Help" thread - but you'll get help here as well.
I hope this helps.
Cheers~ // Shallow
With Shallow! You helped (though the only one-_-)!
I'm glad I could help you~ c;