To start fold your fabric in half. Then cut two pieces of fabric 3 inches wide.
Next, fold down a half-inch of fabric on each side and glue it down with a hot glue gun. Do this to both pieces.
Then, take both pieces of fabric and cross them so they make an X (pictured below in Step 1) the fold one side over the other (Step 2) and then fold down the second piece of fabric. Then pull the two sides so it looks like a knot.
Then, measure the fabric around your head and cut some fabric off each side to fit your head size. (Cut off more then you think the headband will stretch when the hair tie is added)
Next, take the hair tie on one side and pull the fabric through, next fold over the fabric and glue it down. Do the same to the other side.