If I'm following you right Dan (and I'll admit, I struggle with that sometimes. :p ) A mapped drive is just a way of giving a "drive letter" and easy access to a SHARE from another computer. That can be a drive or just a folder on a drive.
So once you share the "resource" you want to share on the machine that has the resource. You then go to another pc and pull up the machine that has the resource. Then you right click and say "map network drive" or whatever it says. Pick your drive letter and some optional options and then go.
So like my wife's computer is called "Boomstick", she has a G drive that is an external that we store our files on, this is shared. From my pc I go to //Boomstick and I see the "G drive" or whatever we named it when we shared it. I then right click that share and map it to my "S:" drive on my local PC. I go around the office and do this for everyone and now I can just say "It's on the S drive" and everyone knows what that means.
A little BONUS is that if you go on the host (Boomstick in this example) and do the same thing she will have an "S:" drive like everyone else. This is helpful for times that files get linked... say you place an image and forget to embed it. As long as the file is on the "S:" then it will still work when opened up on her computer as well.
Hope that helps.