How do you submit a picture without the background?
 

Hi, I've noticed people adding a picture onto the addon download page for information about it and not have the white or solid colour background.

My example is this: http://www.wowinterface.com/download...68-RealUI.html

Anyone can help me on how I do this?
Thank you

Edit: I've sort of fixed the problem. However the image is being resized as its too big. Is there away around this?

It's saved as a PNG file, if something is set as transparent then it will be transparent.

Thank you, problem solved :)