Insert 1/2" if the twisted trim into the seam allowance area where the side edge of the figure meets the base.
Using sewing thread, stitch the trim in place invisibly, working through the back loops of the twisted trim.
After stitching the trim in place, cut the excess trim 1/2" from the end. Tuck the end in place as you did when you started.
Details of the tucked ends can be seen in the next step.