Hi,
Heres a site with most of the editing and creation stuff on it, NGwave is very good for editing
http://www.newfreeware.com/audio/wav/0-1.html
for making your own sounds if you have an audigy theres an audigy plugin from their website which gives you access to a keyboard and loads of sounds, just get a reasonable bass sound and then record the other sounds you require.
e.g I play with the keyboard until i get a good bass resonant sound say for an mg, then add in the shells clinking to the ground, a standard mic can do this then use one of the cleanup utilities on the website above to get rid of static noise etc. (dropping 1 penny coins onto cement sounds good
two things to get to know are fade and echo a gun shot alwasy echos off nearby walls even valley sides so its never a one tone sound it hasd an initial "crash" for the ejectin of gases from the barrel and then this fades away slowly, sound is easy its mixing the fade in and adding the effects thats a pain, even the midi player on xp can do this fairly well.
alternatively open up sound filders in most half life games and you edit one of those wav files , add bass, resonance echo etc its a good building block and most mods don't mind as long as the sound is not the original ie you change and edit it.
cheers
Romanov
