Its a bit more complicated. The jigsaw is a shortcut, its hard to explain... I'll try. There are 2 big pics. The left one, and the right one. Click File. Pick Save Tileset 2, save it, and thats what you can insert into. There are different pallettes, which can be changed. There should be a menu just above the centre pic in Advance Map. That is the pallette changer. Pick the right pallette for the colours you want.
Yeah... That Colloseum cannot be inseted. Its good, but its not th quality that makes it uninsertable. Its the pallettes. The pallettes cannot let me insert it like that, or anything near that. If I could I would, but... Also, the size is hard to make into tiles without deleting tiles we also need... Good though!