Adding custom race

Level 14
Sep 24, 2009
Hi guys!

So I have decided to start my own custom race map (tech-trees are done). But, biggest problem I have is that I have no idea how to add a new race, while keeping existing ones (I need them, so people can play against working AI). What I want to do? I want when you load a map to have a list of all custom races, and you pick which one you want to play. Pretty much like it is done in this map:

So, is there any good soul out here to help me? Just, PLEASE, take into a consideration that I have next to no World Editor experience (I know basics), so try to explain it like you would explain in to 5 years old kid. Step by step.

Thanks in advance!