For Avatars:

click your name at the top near the text "Logged in as:"

select "Avatar Options"
goto: "Upload a new image from your computer" and find the image on your computer.

Press "Update Avatar" and you're done.

While you are there you can back click once and click on "Edit my Profile" on the left side you'll see reference to your personal photo prbably "Edit Personal Photo" or "Change Personal Photo" clcik the link and upload the image the same way you did your avatar and you're done.