I've seen you create a whole bunch of threads recently, asking about all sorts of things, so instead of making any more, I'd suggest you need to slow down a bit, and do a bit more searching before asking specific questions.
I get that you're interested in ROM hacking all of a sudden, and that's great, but you need to, as the saying goes, "lurk more". A bit of reading the forum and looking at other hacks will answer most of your questions.
If someone could post the required reading list, it'd help (I don't have it to hand).
until i can edit graphics, i am first of all looking into changing music soundtracks.
This is revealing. I see that you made a couple of level hacks for Blaster Master, but in all fairness, that isn't really hacking: it's using someone's level editor to make new levels. The very first hacking most people do is graphics editing, because it's the easiest thing in the world.
You download Tile Molester or Tile Layer Pro, open Super Mario Bros, and draw a new hat on Mario's head or something. Boom, you're done.
The next thing most people do is text hacking, which can vary in difficulty. In some cases (editing English games) you can just open it in a hex editor like HxD and write over the existing text (as long as you overwrite it, keeping everything in its place). In other cases, you'll need to learn assembly.
If you REALLY want to get into ROM hacking, ask yourself this question: will I spend hours hacking a game that I couldn't care less about, just because it's a good learning experience? If the answer is yes, you could be a ROM hacker.
And to answer the question of the thread, forget about sound/music hacking. I know what I'm doing, and even I wouldn't bother with that mess.