Save it in the Maps folder, and if there isn't one, create it. By the way, maps should be named using Latin characters; otherwise, the map will be 1KB in size and won't launch.
Don't treat me like a complete loser. Everything is in English, no Russian characters, I've read the entire forum. The problem is specifically with the maps I create from scratch; they aren't in the game (they are present in the maps folder, and the file name is in Latin characters).