Well done young padiwan.
Click on the account details icon in the upper right corner. Currently, in you case, it will be a pink V.
A drop down menu will appear
Select "Account Settings."
The screen that comes up will have a line that states "Avatar" ... "Click the image to change the avatar."
So, Click the image
Select the "Use a custom avatar" check box.
click browse and find the subdirectory the file is saved in (this is the hard part to teach).
When you find the file, highlight it and hit "Open."