It could be a photograph, text document, or any other file (exe, winrar, etc.). All you have to to do upload it is drag it inside the program window, then other people will be able to download it.
A progress bar will indicate how fast the upload completes, and once it's done, you'll get a link that leads to whatever file you uploaded.
Minus is a painless way to share small files. It allows you to pass along tons of images and text with your friends in a matter of seconds.