Is it hand sewing like doing the back binding? I wrap the thread around my needle three times and put the needle in where I want to pull it through. Make sure you leave a little space so the knot popped through does not gather the stitches. Once the knot is popped into the sandwich, run your fingernail over the entry hole to close it. If all looks good, trim the extra thread off leaving a 1/2 to 1 inch in the sandwich.