Contribute form is hard to use

Contribute form is hard to use

Source doesn't suggest that it needs to be an URL, some kind of hint inside the form would be great.

Won't accept 'Picture 2' I took a snapshot and tried to upload it, it wasn't accepted because it didn't have .png, what's worse is that when this error message displayed the form forgot all the other fields I'd entered

I know you want to keep the pattern tap stream full of good stuff, but don't make it frustrating to add good stuff :)