Just noticed, you're on the original B1W1, not B2W2 right? If so, FYI
Anyways, you need to uncompress the overlays with Blz (see here for more info: http://projectpokemon.org/forums/showthread.php?27143-How-do-you-edit-TM-moves&highlight=overlay), open up the correct overlay, and go to the offset.
The subtraction was based off of this: In the grand scheme of things, file A starts at offset X and file B starts at offset Y, with Y>X (so B is located in A); You need to find where B is relative to A, so you do Y - X = Z which is the location of B within A.