a JPEG at the very beginning before the movie starts - how would I do that, please? There is no gap between the start of the timeline at 00:00 and the beginning of the movie. Then, I would like some 'rolling credits' to move up on this 'still' JPEG before the movie proper begins - I presume I use the 'Text' tool to do that?
You can drag your JPEG in front on the video on your timeline. The other clips will move right to allow the insertion.
As for rolling titles, there are a number of templates under the Text button on the Action Bar. Just drag a template to the video track above the one that your JPEG is on in order for them to roll over it.
That's great, Steve - very many thanks!