Basically, take a look at an existing shipset that came from the game - you have to make a directory under Pictures\Races with the name of your race, and then under that you put all the pictures, preceded with the race name, just like with the stock shipsets - so if you wanted to create a shipset called "Zorg" then you'd need to create Zorg_Main.bmp, Zorg_Portrait_Starbase.bmp, Zorg_Mini_FighterSmall.bmp, and all the rest, all in a Zorg directory.
And sorry, the game won't generate the topdown views for you - you have to make them or find them yourself
BTW, IIRC you CAN add your own ships to the demo, you just have to replace the existing ships with your ships (keeping the same race name) instead of creating a new directory for them.