On staredit, there's a column in the left that you get to choose which units and stuff to place on the map.
If you were to get Starcraft X-tra Editor, there's another option that lets you place doodads.
Guedit, or ScmToolkit(best for colors) canchange the players colors to black etc.
All of these programs can be downloaded here:
Map Making Frequently Asked Questions
Use common sense to find the downloads of these programs.
Topic on Unprotectors:
Don't post a link here or a download link here. Unless you want to start cleaning my bathroom for the next 3 years. Man it's starting to rott in there.