How do you play Starcraft campaign editer maps after saving them?

After saving the map, run Starcraft. If you wish to play on multiplayer, click create, and then beside the map selection, there will be a button called "Browse". Click that, and find your map from there. If you play signleplayer, you double click on "up one level", and then the map should be in the downloads file.

(Note - this is for Starcraft 1.16.1 Brood War. Other versions may have different ways of finding the map)