Hit the person icon at the top right of the screen next to the text message looking icon. In there hit account details. The third item down is your avatar. Click on that. There will be a choose file button which will allow you to choose an image saved on your phone. That's it.
Don't get confused, your avatar is the only image you can post directly from your phone. To post other images they have to be on the internet (URL), so an image hosting site like imgur has to be used.
When someone figures out how to exit a thread in this new format without using the back button kindly drop it in here.
