Hi Gary,
The feature to do this was introduced some while ago, it's called "Photo Mats (uneven borders)".
See screen shots below.
Place the mage in the queue and right click on it to select Photo Mats
Enter the border sizes with Grow Mat selected, OK.
Select the mat on the print preview, you cannot easily see it if white but click just outside the image.
Select the crop marks required.
NB. you can have multiple mats to create several borders on one image.
Hope that helps.
Terry
PS. There is a video for mats
https://www.youtube.com/watch?v=Rl8Q4fP7rYM&feature=youtu.be&hd=1Or click the red V bottom right on the Mats dialogue