I NEED HELP ON ROM HACKING

[SpY ooX]

I need help
I was looking at all the rom hacks people have made and was wondering if some one could tell me how they did it.
I know they changed the sprites but how did they get to the sprites to replace them.
Is there some help files i can look at on some site or a program i can use do make my own thank you.

[Mockery]

http://www.romhacking.com

All the info you need is there.

[SpY ooX]

thanks alot man