AW will not accept anything over 100 KB. Also, as a novice, you are limited to gallery space. Keep logging in and when you become a citizen you will get more gallery space.

Edit: I just checked your image gallery, you have used up 66 of the 100 k you are allowed right now. If you are trying to upload something over 34 k, AW wont take it. You might want to delete and resize the 66 k image you have in there now, or use something smaller so you have space for several images. Once you advance to citizen, the space allowance moves up to 250 k.