I have no idea where you have a problem so here’s the whole procedure.
- Find an image of jpg, gif, or png format that’s at least 40×40 pixels and save it on your computer
- Click on “My Profile” in the top right corner
- Click on “Edit Profile” in the upper left under your name
- Where it says “Avatar Image”, click Browse, and find where you saved the image
- Click “Save” at the bottom of the page
If this didn’t work, explain in more detail which step failed.