Clan pics take a long time, and what you need to do is
1. Have shaders (If you want it to be at least a little better than crappy)
2. A shader that provides a sold color background.
3. Screenshot them, and open them up in an image editing/pixel manipulation program.
4. Make the background of the image transparent.
5. Do this repeatedly for everyone you want in the pic and compile them all in to one image.
If you have any further questions that you need urgently answered, PM me.
I also think this should probably go in Beginner Sanctuary.