A lot of people come here in search of magic bullet cures. There are none.
There is no program that will open a GBA ROM - or any ROM, for that matter - sift out the graphics data, marry each tile with its appropriate palette and then hand you the results on a silver platter. Whatever you're trying to do, it will take some work and knowhow.
Begin with learning the basics. Check out the documents and utilities and try a simple graphics hack, like changing the font in a game or altering the sprites.
I don't trust either of those Cat's credentals. One is working through an inch of desk and the other is looking inside an empty computer case! I smell a scam...