Where can I find some detailed instructions for a bar soda gun?

I work at a small restaurant bar and need to know how the soda gun works. You know the kind, handheld device with multiple buttons you press for dispensing various liquid refreshment.

I need to know the ins and outs of the thing, the real nitty-gritty of how it works, because no one else around here does nor do they care to learn.

I called Coca-Cola, but they said that there are no instruction booklets and the best they can do is answer any specific questions I may have. I don’t have any specific questions, I just need to know everything I can about running the darned thing.

What’s to know? You push the button, liquid comes out.

How to build your own home carbonation system. Anything in here help?
http://truetex.com/carbonation.htm