There are basically two ways to create a room:
1) Online using the *add command, and the various room editing functions.
See the documentation about *add, *replace, *save, *reload,
*name, *set, and *rm in the dm_cmnd file..
2) Offline with the editor.
It is important that you use the *reload command to reload any
changes you make in the editor if the game is running while you are
editing offline. If not, the changes you make in the editor could be
erased by the game.