How to post an avatar

Simplicity itself!

Hover over your name in the Nav Bar and a menu will appear
Click on Avatar



Then you get an overlay



Click on Browse and choose a picture from your pc
Maximum size dimensions are 200 x 200 pixels

 

I think if you upload a bigger one it will automatically reduce it down to 200 x 200 for you

Best if you upload an image that is square though.