Hey! Here's the easiest way I can think of to post pictures... after all, it works for me, so it MUST be simple!
First, register at www.photobucket.com. It's free, easy, and all around great! Once you register, follow the instructions they give you to upload your pictures onto their server. They give you a pretty good amount of room, so you should be okay.
Then, they will give you 3 seperate codes. One is a tag code (perfect for using in your "avatar" image... you know, the little thing that you put below your username... yeah.. It starts with an) One is a URL image, to link directly to your image via a link. And last but not least (trumpety sound) is your IMG code. You can use that to paste into your yellow comment box, and viola!
Now, I'm gonna feel really dumb if I got it mixed up. So let's hope I didn't!