Add a new track, drop it there ABOVE your main video track. Use track motion to size and position it. It will float over the main video. You could also you use FX pan/crop.

Instead of having it just sit there you could get more creative and have it spin in and out when needed, grow in size and appear, disappear, etc.. With either you can set position very accurately if you click on the top icon within the work window that opens.