How can I draw a line around the boundary of a piece of real estate in a video clip with elements 13?
Premiere Elements 13 on what computer operating system? Have you updated 13 to 13.1 yet using an opened project's Help Menu/Updates?
To your immediate question...you could try something like this
In this scenario, you start with your video on Video Track 1 with the Timeline Indicator placed at the appropriate Timeline content place.
The line Titler file created will automatically be placed at the position of the Timeline Indicator.
Text Menu/New/Default to Titler/ and select Shapes Section.
The Titler file goes to Video Track 2 above the video on VIdeo Track 1.
Select the Line Tool in the Shapes section, and draw your line on screen to correspond to where you want it to appear in the video below.
Your line image is the line on a transparent background where the content below shows through the areas of transparency in that line image.
Please consider. If any questions or need clarification on the above, please do not hesitate to ask.