No. You can in fact put code and data anywhere you want to, although it's optimal to place related routines near each other because short and word sized branches take less ROM space and execution time than jumps. Yes, you should overwrite the file that already exists. As I said before, you can place data anywhere you want, but it would be good to place the new files near the one that already exists, which should look like this: Code (Text): Obj09_MapRUnc_345FA: BINCLUDE "mappings/spriteDPLC/obj09.bin" You'll want to rename this label to 'Obj09_MapRUnc' as the guide says, and then put the other two files right under it. Tile data is located in the "art" folder, with different subfolders for different compression types. For object sprites, you will also need to work with the sprite mappings (found in mappings/sprite) and possibly DPLCs (found in mappings/spriteDPLC). Flex 2 is a great tool for editing sprites.