Here is a link with fringeinstrutions from Veronika with pictures how to do.
You trim from the back side and then it can be pulled through to the front.
When you complete your design you clip the threads on the back side of the design. There is almost a "cutting line" from the meeting of the bobbin and the top thread. Clip this and pull the threads to the front. Make sure that you do not clip all the way through the fabric, and only the threads. Want to ask how we know that? LOL Good luck.