Exactly what Kaliyuga said !!!!
IF you want a cut-scene at the begining, middle, end or inbetween missions in one of your campaign you can do one of hte following :-
1. Make a cutscene in the MISSION part of the Editor and save this, you would then use this MISSION for a cutscene in your campaign.
2. Exactly as above but make the cut-scene in teh Intro or Outro part of teh Editor, save and use as a CUTSCENE...
I think it is down to personall preference and ability ;D
Rhys