Map Making Community

I'm wondering if there are any communities or groups who focus on making maps for Starcraft 2. I'm curious, because I feel like a lot of the good maps are termed "community maps" meaning that it wasn't Blizzard who made them, but where is this "community".

Also where can somebody new to map making find assistance and advice. I don't mean "this is how you add a doodad" but "this is why your map is good/bad/week/prone to rushes" etc.

(talking about competitive 1v1 or team maps, not custom arcade maps like marine arena)

Newbie Tuesday on map making FTW!~ :D