An avatar can be basically any image or animated .gif. There are a few rules. First, it can't be objectionable. NO PRON! And must be in good taste. Nothing to suggestive, violent, racist or all that. Second, the image can be no larger than 60x60 pixels or 48.8 KB, whichever is smaller. So, find an image you like. Resize it to 60x60 or so. Go into User CP on the menu above. Click on "Edit Avatar". Then look near the bottom. There should be a place to select a custom avatar. Input the location of that image and it will upload and be set as your avatar.
Again, will you stop beeing so ignorant, ACDSEE will get you your 60x60. You are having a hard time getting your image down to 60x60 because the image was not a square from the start. Take it and crop the image into a perfect square. Paint, ACDSEE and other programs will do this.
it has to be as small or SMALLER then 60x60 not exacly 60x60 you need to uncheck the box that says constrain proportions.. so you can adust each size individualy but your pic will look funny..
Do a google search on avatars. You'll find a few cool sites that have forum avatars for free and they have tons. If you want something different, I'm sure you can find something there.