Click the browse button next to "Upload Avatar from your machine".
A separate window will pop open:
Navigate to where you pic is on your hard drive.
Click on that pic.
That separate window will disappear and you'll be back at the knittinghelp.com profile window.
Click submit at the bottom of the page.
This how I added my little clip.
What format is your Avatar? I saved mine as a j-peg. If your pic isn't working, perhaps the site doesn't recognize the format...
Hope that helped a little ...