Chances are the errors you encountered were due to...
1. They used an editor that allowed stacked placement, like the X-tra Editor. If this is the case, you will need to open it with something like this to look at it.
2. They protected the map. If this is the case, unless you know what their password is,,, you will never open their map.
The X-tra Editor can be found at,,,,,
http://www.campaigncreations.org/starcraft/programs/index.shtml
Get good with the standard editor, before moving up to a placement editor. It's always better to learn from the bottom up.
As far as the map protection, I use the SCM Toolkit, I think that the GU Editor does it too. SCM Toolkit can come from...
http://www.angelfire.com/ab7/scag_home0/design_tutorial.html
This page also has a tutorial on stacking minerals, yes that's right the dreaded mass money maps.
Again, get good with the original editor first, then move up. The chrome on the car doesn't matter if you don't know how to drive it.
