Hi, i would like to change the weaponlaunch and guns sounds. How do i edit them?

You can send me your sound material and i can do it for you

Or you try out audacity (its for free) http://audacity.sourceforge.net/download/ and get it on your own

I was finding that audacity (and others) were internally converting the input format to a higher definition and then converting it back down when saving, which meant that a lot of the time I ended up with more hiss/crackle than actual sound.
I ended up using a really old editor that would keep the data in its original (8-bit) format while editing though I had to write a couple of programs to convert between raw-pcm and wav (simple add/remove header) as it would only work with wav format.