To make an icon: 1. I use MS paint. It came on the computer when I bought it, and it came in the big cow box. I find it easy. OPEN UP PAINT!
2: You have to resize the the white box. AIM icons are usually 50x50 pixels. For IMbum.com, they must be 50x50 or they will be resized. If you make doll icons and you put them on your AIM screen name, they get kinda goofy looking, so I usually make them 48x48. Anywoo. Your box will probably look bigger than this, but I have provided a lil picture of the box I have so you know what I'm talking about.

Ok, now click on the right bottom corner and make the box smaller so that it is sized 50x50. You will know when it is the right size, because there are numbers at the bottom of the MS Paint window that change as you make the big white box bigger or smaller. Save this as blank.bmp or something. Just save it as anything, you have to save it so that the next time you open paint, you won't have to resize the white box again.
Now you can put what ever you want in this box. Knock yourself out, woadayy.