Sandman

If it's a multiplayer map, read Step 7 in the Map Editor Walkthrough.doc file that came with the editor. If it's singleplayer you'll need to place the map into the GameData/Data/Art/Maps directory (you may have to create a new directory), rename it to the name within the tags in Planets.xml file. That'll make the game use that instead of the original in the .meg files. You can't run them directly from the editor.