Adding an avatar (a small personal image like the one on the right) to your profile is pretty easy, and is done in a way that is very similar to the process of adding an attachment to a Forum post.
First, you will need to have a graphics file (.jpg or .gif or .png), no larger than 180x180 pixels, and no larger than 200Kb saved to your Desktop.
Drag your graphics file to the avatar space on your Profile page.
Lastly, remember to click the Submit button at the very bottom.
That should do it !!
* Tip: To reduce the size of an image, I like to use EasyCrop from Yellow Mug Software.