Ok will do
First clean out your case.
Take out everything but leave the frame in tact.
Sand it with 1000 grid sandpaper.(waterproof)
You dont have to sand it down till bare metal but sand it lightly.
After you sand it, clean and dry very well.
Get a primer for the surface you are spraying. ( Duplicolor brand)
Spray 2/3 layers of primer but be careful, dont spray to much. You can better spray 4 times thin, then one time to thick. Let it dry for 24 hours.
Look for uneven spots in the primer and sand those spots down very gently with 2000 grid sandpaper.
Clean the case again with water and soap.
When you are done with that you can start spraying the color.
Apply very thin layers.You want to spray more at once but really dont do it.
It takes about 4 times before it begins to cover completely. Let dry for 4 hours.
Look for spots again and sand it down with wet 2000 grid paper.
Then spray the final coat.
After the final coat you can spray a protective clear coat on top. Spray 2 times for a nice result.
Always use primer, color and clear paint from the same brand. I recommend Duplicolor paint.
This is very nice guide.
http://www.mnpctech.com/case-mod-paint-computer-pc-case-mod-how-to.html
Dont expect a result just like it, but it will help a lot.