Use the .raw files from the DEMO folder in your blank game folder. alo make sure that the new game you have created, is in a special folder (not blank)
EDIT: I know that this isnt how it should be, but it works. In that way you can´t use own tilesets, but you gotta find out yourself. AND: maybe you take a look into the .bmp´s before you convert them. If they are black&white, well hell, you have to find the right ones (editing kit\demo\source, i believe). But after a short time you`ll gonna find out that the standard tiles are waaaay not enough (i use my custom tileset)