The internet is an amazing resource for anyone crafty. I found this free pattern
here. I unfortunately didn't take all step by step photos, but you should be able to get the jist of this.
First, I downloaded and cut out the pattern. Then I matched all of the labeled notches and taped them together.
Second, I traced the pieced pattern onto a roll of paper to make it easier to cut out the fabric.
For both the front and the back, cut the fabric on the fold. Sew with 3/8" seam allowance. The great thing about knits is you don't have to sew a hem if it achieves the aesthetic you are going for. Here is how it turned out!