Where can I find a good pokemon avatar?

Well, if you open up the User Control Panel, you can find a good deal of avatars already loaded and ready for use:

1. Go to the UCP (link above).
2. Click "Profile" from the left-hand menu.
3. Click "Edit Avatar."
4. Hit "Display Gallery." From there, you can select avatars from different categories. Just find one you like and hit "Submit" at the bottom of the page.

Alternatively, you can request an avatar from one of the several shops in Sunyshore Market. For help on uploading an avatar from your computer, check out section 6.1 of THE BIG THREAD THE ANSWERS ALL YOUR QUESTIONS. From there you should be able to figure it out, but if not, don't hesitate to ask for more help.