User blog comment:SamRudi/ok im sorry for asking this again but/@comment-1024726-20090816014332

I use Inkscape, a vector graphics picture editor that uses SVG, a valid picture type on this wiki. Inkscape is a free download and (I think) works on Linux as well as Windows (and it may work on Macs as well). Inkscape's only flaws are text-uploading issues and compatibility problems with other formats such as PNG, JPG, and GIF.

As for your problem, like I said, you need to save the pictures in a valid picture type. When you save the picture, you must find the drop-down box that shows file type and select Portable Networks Graphics (PNG). If your picture is animated, it should be saved in GIF. If you are using a vector graphics editor like Inkscape, select Scalable Vector Graphics (SVG). (Inkscape users, select Inkscape SVG.)