Where to start to learn mapping?

[fscii]

Hey I figured it out. I had to unjoin the wall (floor and ceiling joined w/f and g) and then make a window cut out (individually raising/lowering cube columns) and then drop in the a/c. very cool. Thanks for the help guys.

I don't expect to be a mapmaker thats way out of my league but I do want to be able to tweak existing maps where you say "I wish it had..." now it will have lol.