>I've generated an application.prg with the application builder and don't know where to put my main program code. Should I write a separate main.prg? If I do, how and where do I interrelate the _app and a main.prg? I've built my forms and can run them individually in the project manager. How can I "do" and release them from a central program? This basic subject is nowhere in the help file. I'm really stuck!

What you could do is open the project in the Project Manager. Expand Code node, expand Programs node. Look for the entry that is in bold. This is your MAIN prg file. Somewhere in there where you think it is appropriate, insert a procedure call:

local llRetVal
llRetVal = MyMainPrgCode()
if not llRetVal
   return .f.
endif

Go to the very bottom of that prg file, and add the following:

PROCEDURE MyMainPrgCode
   * put your code here
   IF ALL_DID_NOT_GO_WELL
      return .f.
   ENDIF
   RETURN .t.
ENDPROC