Does anyone else have trouble uploading files because of the file size/type? I know all the requirements for uploading a file but it was super hard to resize them to get it just right, is there an easier way to simple save a file in the right size?

Hi, I'm new here so I'm not sure if I'm doing the right thing in the right place, but I really need critiques on my 'Flowerburst' design

http://www.threadless.com/critique/55966/Flowerburst

Anything you think I could change/make better is welcome! Thanks