Get some coordinating fabric and just start adding borders. Here's a picture of a top for a couch throw that I'm making for DD's teacher for Christmas. It was started with a panel. The large snowman and the six smalls were the original panel. I cut the small ones off and added two borders the the big one. Then I added the green between and the gold on the top and bottom of the small ones, added them on, put the gold on all around, then just kept adding more borders until it got to the size I wanted. There's also a very small flange in there between the first red border and first green. I hope this helps. I usually add a side border then go across the top and the bottom. Some people miter the corners but that's something that you might want to wait on until you have a little more experience.