Still image with video playing in background

Hi,

In my timeline on V1 I have my video playing, and I added a still image on V2, and set to frame, then in Effects I scaled the photo. 

The photo is cropped vertically, so there's a bunch of empty space on the left and right sides, and that's showing the video playing.  I want a black background behind the photo, so the 5 seconds it's on screen, the audience isn't seeing the motion picture in the background.

To solve this problem, would I need to add Black Video in Project window and place that in my timeline on V2/V3? 

What if I want to add effects like dissolve on the photo?  Would I then need to add the effect to both the V2 Black Video and the V3 Still Image?

Thanks