Go to your profile page and click on Appearance button for changing your player avatar. If you want to upload a picture to your profile avatar then click on that button and follow the prompts.
Happy Golfing!
Also if uploading a picture from say Photobucket, make sure you delete the HTTP:\\ that's already in the box. Or else it will not load correctly because you will then have 2 HTTP:\\ in the box instead of one. Blank slate before copying & pasting it.