Go to your profile..
Then on the right.. Just beneath "modify profile", you will see "forum profile information".
Click that and you will see this below.
Check one of the two choices. Either "I have my own pic", or "I will upload my own picture".
Most likely you will be uploading your own picture. So check that, and then use the "browse" button.
Navigate your way to what ever folder you have the avatar/profile image stored and select it.
Just a reminder.. To select your image. Just right click on it, and scroll to "select"
Once you have saved your avatar/profile image... Go all the way down to the bottom of your "forum profile information" page ( the page your on) and hit "save changes".
All done !