Take a look at the Legion umpire manual. The last 40 pages or so contain a mechanics primer with each situation shown ina useful diagram.
Go to
http://www.baseball.legion.org/forms/umpiresmanual.pdf
It doesn't cover detailed mechanics like who has the tag up with R2 and a fly ball to right field, but if you study it you'll learn in a hurry where to stand and where to go on a fly ball.