Higher numbered tracks overlay lower numbered tracks, to create a PIP (picture-in-picture).
If your still image has a solid background - which can be accomplished with a graphics tool - then that background can be chroma keyed out (so called "green screen"), leaving only the subject to be overlaid in PD. The background doesn't have to be green. Just be certain that it doesn't contain any colors that are present in the image that you want to retain.
As for freezing the action, one method would be to take a "snapshot" still frame from within PD, then insert that frame into the sequence and extend it for the desired duration.
This message was edited 1 time. Last update was at Feb 05. 2015 21:48