I'll cover this in much more depth later, but it would be fun at this point to add some bots to the level. Make sure your map name starts with DM- and save your work. In the editor, click the Build All button to the right of Build Lighting.
Save your game and run it. Open up the console by pressing Tab, and type addbots 1. A bot should appear, and you can kill it.
To add more bots, add more player start nodes, rebuild all, run the level, and type addbots [number] in the console. Have fun with it. Try adding some additional rooms, and make a more interesting layout. See if you can make ramps to rooms at different heights, or raised platforms inside the room.
So we have now tested our map with bots and have an idea of what our map will play like with these two rooms and a hallway.