http://www.propane.tx.gov/commercial...mpcosystem.pdf
This link talks you through the main steps.
The main mixture valve should have markings that say R and L (Rich, Lean). Adjust as necessary.
Don't go to lean though. I was a bit lean one run and the exhaust got so hot that it turned a red cherry bomb half brown
Pretty much all of the gotpropane stuff is impco brand