I watched but they make it so complicated. Much easier to join strips as they said except I never join with a straight seam since it leaves to much bulk and gives the eye a path to follow. But once all of your borders are joined mark your centers and pin from the center out. Begin and end sewing 1/4 inch from edges. Sew all four sides then align the corners mark your 45 degree angle for sewing sew then check to make sure everything lies flat and then trim seam.