Sorry man, didn't mean to scare you off. So many guys did this to me. Every time I asked about it, I heard something negative. The reason why is so many people use it wrong so they don't have much good to say about it.
The easiest way is to get a digital meter that controls your Co2. Plug it into something else digital that controls your exhaust fans. That should stop you from wasting Co2. Set your Co2 from 1200 - 1500 ppm. There's a more complicated way but if you let money solve this problem, you could really notice the benefits of Co2.
I must mention this, if you aren't running every other factor in your grow enviroment close to 90% efficiency (as far as what your plants want), you won't really notice what Co2 can do