How do you change sounds for weapons on BM1?

Ok, so flashgate died out, but I'm bringing it back.

I don't have the .fla of it, so I've been using the extracted resources from the swf as well as lots of other things to make a fuller and more complete flashgate.
It's not identical to the other, although because lime green happens to be my favourite colour I'm keeping those lovely green menus.

Anyway, to the point... So I'm redoing the weapons list in the preloader and the weapon sprites. Completely new set of weapon sprites not just renamed BM ones, and one of them is a railgun - but I'm really not sure how to change the sounds.
If someone could tell how to give my weapons sounds this would be awesomely helpful.
Thanks in advance if anyone can help me, you're a star.

Oh, and for the record, I'm putting time and effort into this so it doesn't just look like a plug-in, I'm doing this and I want to do it right.

the sound is in the library. you have to make the identifier and all that the same

You mean you just associate the image and the sound by putting the name of the image in the indetifier box thingy? ... that was easier than I thought...I'll try it out now...