Need quick, basic info on 3 person mechanics!!

[Lotto]

I know this has been asked before several times, but the search function has been disabled so I don't know how else to get the information so I'm asking again.

I'm strictly a 2 person mechanics HS ref and I've been asked to help out at a scrimmage tomorrow using 3 person mechanics. I know some of the basics, but I could use a quick tutorial. Is there a web page or a download somewhere that I could refer to?

Thanks for the help!!!