This can be about anything like, which is your favourite armatar, your own armatar creation, basically anything to do with armatars because I simply love them.
You need to get a painting or graphic creation programme. Like msPaint, GIMP, Photoshop, Illustrator, Inkscape or anything like them that will make sure you can make a picture and save it as a png. Then you will need to make your picture, preferably in a 200x200pixel size, though, if you are working with vectors, any larger scale that scales well down to 100x100 is alright. The same will not be recommended in non-vector pictures, and with those you should probably keep the biggest version at 400pixels max. Anyway, with that done, you need to save it as a png (but with a solid colour background, not transparent), as jpgs have a tendency to lose quality, especially if you use msPaint. Then you upload it to an image hosting programme like Photobucket or Imageshack and you have a custom armatar.
Of course, to actually be able to use it, you will have to wait until some admin decides they will allow a new armatar contest like the one SubZero got theirs from, or that they implement the feature of uploading your own armatar. Otherwise you just have a very nice 100x100 picture you wish you could use.