Tom welcome to the site. When I started learning the Tac thing I was using a VXIII 6.5-20x40 Leupold that had moa knobs with a mil-dot reticle. I was a little lost on how to use the reticle. 1 day a new shooting buddy was kind enough to invite me to shoot with him at his home where he would school me in how to use these types of scopes. By the end of the day I was ranging targets with the reticle and getting within a few yards. Happy, happy, happy.
I have now gratuated to Mil-Mil scopes. I've googled and read some here on the net, decent info, but nothing better then having someone work with you FTF. Whatever you do make sure the scope is either Moa-Moa or Mil-Mil. I believe there is a shooting program you can find on the computer and play around with, I can't remember the site rightnow, if I find it I'll let you know.