How so I put up that picture of myself, or
How do I get an avatar?

Click on "My Profile" which is near the top right of the screen.
Then click "Modify Avatar"

Or use this direct link:
http://forums.mormonletters.org/yaf_cp_editavatar.aspx

The Board Software will automatically resize your picture to 50x80 or less.
You can upload a jpg or gif from your computer, or point to one hosted elsewhere on the internet.