Explain these rules to me please.

Terminology is going to vary slightly from system to system. In my experience with the wing-T, Gaps are defined as the space between two linemen. A gap between the C and G...numbered as 2 to the right side and either 1 or 3 depending on how they number the center. B gap is between the G and T, numbered 4 to the right side and 3/5 to the left. C gap is between T and TE, numbered 6 to right and 5/7 to left. Beyond the TE to the sideline is D gap, usually 8 to the right and 9 to the left. Playside is which direction the play is going...simply right or left, and backside is opposite. For instance, if a play is going to the 4 hole, anything from the 2 hole back to the left is "backside" while anything to the right of there is "playside"...again, these definitions may vary slightly. A coach may chose to just call the entire right side "playside" and the center and entire left side as "backside" for that run to the 4 hole. If you are speaking for specific lineman, then any gap toward the play is "playside" and any gap opposite the play is "backside".

As far as your rules above...

Gap--Down--Backer--that is a blocking scheme (rules for your linemen). Tells your linemen that they are to block the playside gap as their first priority, if it is not threatened, then downblock your backside gap, if there is nothing there, attack nearest LB. The Wing-T is a nice system for linemen because there is very little thinking to do...just about every base running play is gap, down, backer blocking rules.

Hope this helped. Feel free to email me if you have any other questions at kelly.fbcoach@gmail.com