Fold and press half an inch of the bottom seam. Fold and press again, then finish the seam with a straight stitch.
Fold the top edge over, leaving enough room for your elastic to go though. I used 3/8 inch wide elastic. Press the seam down and sew close to the edge with a straight stitch. You only need to fold the edge once, as the bandana already comes with a sewn edge.
Pull the elastic through the opening and secure the edges with pins. Close both edges with a straight stitch. I used an 8 inch piece of elastic in this top.
Use the leftover fabric to make the straps for your top. Cut two 2 by 8 inch pieces, fold in a half an inch on both sides and press. Fold the whole strap in half, press and finish with a straight stitch, keeping it close to the edge.
Finish the top by securing the straps to each side. Make sure that the seams on your straps are facing outward. Now your bandana shirt is ready to wear.