Newbie question about clean edges

Please be gentle lol I am about as newbie as they get, with a diy loom made of cardboard. On to the question, how do y'all weave the sides and ends back in neatly without scrunching up the rest of the weave? I'm so anxious that the horizontal and vertical threads are going to pull right out, but I don't want a fringe.

And do you have any advice for someone as green as myself that online tutorials don't always make apparent?