PintoMan,
On the menu at the top of the home page (when logged in to the site, not via Mobile) hover over 'profile' then click 'forum profile'. You will see a section where you can manage your profile plus an area where you can upload an avatar picture. Select 'upload avatar' and use the browse button to select your image, once selected, scroll down to the bottom and select 'change profile'.
Addition: Got your email as well, you mentioned that you went into the profile section "but it did not work" - need more information. Is your picture a .gif or .jpg (most common format)- others are allowed but some may not be as there are too many to include all. If other, can you change you pic to one of these formats?
Can you post a pic in this thread? If so, you should be able to upload a pic to your profile.