Okay, time for the "SC Goto Guy" to step in and help...
First mistake... Using Starforge. While it is a good program for SQUARE terrain, it is shit for everything else. When I was using it to make square terrain, every so often when I saved the file, SF would corrupt the file and thus it could only be opened in SF. I got tired of this and stopped using it, I recommend you do the same.
I highly recommend that you use only two programs for making maps, these two are...
StarCraft X-tra Editor 2.5 - I use this for Location placement and Trigger editing. The trigger "editor" in it is like the one found in the classic StarEdit that came with the game, only it has a LOT more function.
and
SCMDraft 2 0.6.0 Prerelease 1 - I use this for everything else. Terrain, both Isometric(the triangle shape "brush") and square. Unit placement, etc...
Those are the two programs I use to make maps, and I've been making maps since SC was released, those are the best two I've found to date. Many would argue that X-Tra 2.6 is better then 2.5, my argument is 2.5 is more stable then 2.6, even with 2.6's "Fix patch."
So, remove Starforge, download and install SCMDraft 2 and have some fun with it.
If you need any more help, ask me and I will probably have a solution for ya.