If you asked how to post a picture in your profile, it's easier than you might think.
First, you need to have a picture stored on your computer that you want to use for your avatar. Make a little note to yourself where it is stored.
Go to the top of this page and click on My Profile. Scroll down the page to the Avatar section. There is a box with a button called Browse. Click on that, then find the file where the picture you want to use is stored. Click (or double click) on that file, and, voila, it will show up in your profile.
pm me if you're still having trouble.