it will save your .mis file into the folder of the map you started with,look in add-ons for the folder,take the.mis and the .ter file and zip them up,then place the zip file into the add-ons folder and start the game,your map should be there,you will also need a text file, go take a zipped map file and look at the contents to see whats in there there should be a
.mis file
.ter file
a text file with the name of the map and your name,dont forget to take a screen shot of your map and put it in the zipped file too.