CO2 Questions

my buddie and I just started growing and are 3 weeks into flowering and we are buying Co2 tank and the regulators. If anyone can just give us some advice on using it and setting it up would be helpful.

I'm a c02 skeptic for most situations, you almost have to be growing in a vacuum for it to really be effective. And temps need to be high enough as well. But I'm sure there is a thread / forum here that helps with c02.