Adding your avatar to the system is easy

Go to account >> avatar to get to the place to add your avatar (Profile Picture).

If this is your first time there, click browse (Otherwise its choose file) to bring up your local computer and find the image you want to use.  Then select it and click open.  Once you have it in there you may have to refresh your screen to see it being displayed.  

In the right hand column is the choose avatars block.  If you selected your own image you should see it in this block too after adding it.  Below that are cartoon type avatars you can also use.  Find the cartoon avatar you like and select it.

The avatar that will be used has just a single red circle X, whereas the other icons have an additional green circle check mark.  

Adding an avatar should be one of the first things you do so that other members can SEE you.