Help for Hackin a NES ROM.

Hey guys. I've got a question. Does anyone have any hacking tools for a NES ROM? 'Cause I want to Hack the Mario Bros. NES ROM, but not so complicated, I only want to change the Mario Sprite into one of my own sprites and change the Title Name. So, does anyone knows how to do that? Thanks in advance, Kiekoes.

Try looking around here:
http://www.romhacking.net/