Continue working around and pressing the fabric down with the iron.

Keep on going until you have a kite shape like this.

Now, go back to the edge you started with and unfold that edge and then fold the backing fabric back onto itself by 1/2" and finger press down.

Now, fold that edge over again so that you now have a 1/2" wide border on top that has a finished edge next to the window fabric (since there is 1/2" of backing fabric folded under that). Finger press this down.

Working counter-clockwise, do the same double folding thing with the next edge. Pay attention to the size of the borders you're creating, as they should all look a uniform 1/2".

Continue working your way around. The fold of the edge you just finished will help hold down the previous edge you folded.

Keep going....

There, we have our kit shaped block all finger pressed now.

Press with a steam iron to set the folds.

Now, we're going to stitch down those folds in a counter-clockwise pattern. So set the needle down into the fabric so that it is just inside the fold line and just less than 1/2" from the edge of the window fabric.