Okay Mish - let's back up a step and see what you are really trying to do.
An "avatar" is a pic that is going to show up in the left-hand column under your name. You set that up in your user profile area under the "upload avatar ... " area.
From where your image tags are showing up ... it looks like you're trying to add an image to a message .... like WayneT's "flag", or MJ's "burger". That's a different situation - that's playing with inserting a pic using HTML codes. Like this ....
To do that - you have to have an opening "[img]" tag before the url for the image and a closing "[/img]" tag following it. From the examples I saw of what you were doing, you didn't have a closing [/] tag. For example, for the barbwire - you would need the lines to read: "[img] http://pages.prodigy.net/bestsmileys...eanimation.gif
[/img]" to see:
It's hard trying to show the codes since they try to do things. The big thing is there can be no spaces between the opening "[img]" and the closing "[/img]" codes.