I love the look of piping. It's something really easy that really adds to the project.
What you need is fabric strips 1 1/4" cut on the bias. Bias cut is when you cut fabric at a 45 degree angle to the lengthwise and crosswise. You also need twine, rope-ish, etc. I have this pre-made piping that I found at a thrift store, but it doesn't matter what you use.
See the round side of the piping?
Sew the whole strip.
To overlap, the piping ends will tuck under each other. (At the left of the picture.) You will have to sew over the round edge to tuck the ends under. It may seem weird but it is very accepted when using piping.