Hello,
 
If you are talking about the bundled report builder (ENDUSER.EXE *I think*), you can only move fields around.  And actually not much around at that.  You can also add text and other objects.  
 
Things you can't do: add fields from the database, create sub reports, filter items, etc...
 
It's been a long time since I looked at it, but I seem to remember having these troubles a while back.  We purchased the compiler (from ISTS) and now we can do basically anything we need.
 
As far as a reference, I can't really find much either.  There is a help file that comes with the compiler but the documentation on the report builder portion is lacking.  If you have ever used another IDE like VB or something similar the learning curve will not be much at all.
 
Keith