Yeah, Crabator's code is pretty messy, I should clean it up.
You can look at he example "
TileMapRAM" from the Gamebuino Library. It show the principle, but in this example the map is stored in RAM, which is a very scarce resource on the Gamebuino (2KB). To spare RAM, you care store arrays that wont changes (bitmaps, maps...) in the flash memory, aka
PROGMEM (32kB). An example of tile map stored in PROGMEM would be
UFO-Race, which is much cleaner than Crabator.