That one is actually not self evident;) Minecraft tends to think that everything you do, you do inGame, so they spesify everything as if you fire off commands from the inGame chat console. Using the server console from outside the game (either by running the java manually, or byusing a launcher that opens a command window) is not mentioned a lot. You just kinda have to know (or guess).
Also: If you areasking, there are probably others out there also having the same problems. 