combustion tracing

[Zacatac927]

hey, i know i am going against my L.I.U.I.T.M thing but since i have and have googleed it i need your help,

i just got combustion and i cannot figure out how to put another video/whatever over the first layer to have it tacking on that same line.... like i have a shot, me turning the camera, and i want to put a picture of me in the frame, so i have both the video and the pic in the bin but i cannot get the pic to show up

any help would be useful

thanks,
zacatac