The only method I know is, using the Timeline view, to place the cursor exactly at the point where you want the freeze to begin, choose (via the Edit or possibly the File menu [I think, MEP 16 is quite old]) to Create Still Frame.

Cut the video at the same cursor position, drag the section of your video after the cut to the right to leave a gap, insert your still frame and drag it out to last for as long as the freeze is needed. Close the gap, if needed, by dragging the right hand side back, ensuring that all the video objects are placed exactly next to each other to avoid gaps in your video output.

View the section, check it is exactly as you want it to be, adjust if necessary.  One thing to bear in mind is that for the duration of the still image you will have no audio track.

Jeff