Click on "My Home" (not Home) in the first bar across the page

Go down to the bottom and click on Personal Preferences or something like that

Down near the bottom you can enter a URL for your avatar. I think it has to be publicly web accessible, not just on your hard drive.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8