How to get image to loading screen??

[Mini-Me]

I might be stupid or just blind, but i have been looking through these forums and i cant find information how do u get a picture to your maps loading screen? i took a screenshot and i would like to put it to the loading screen, how do i do it? what type of file type screenshot should be? And i would also like to know how do u get the picture to show up in the place where the map is shown when u are in a internet game and u wait people to enter and it shows the maps picture on the right, u know what im saying?
If somebody got the answer i would be thankfull if u tell me.

 

[Sopho]

I've done a Custom Loading Screen tutorial in the tutorial forum