Fold the long strips in half and tie them onto one 13-inch strip (the "holding string") using a Lark's Head. Say what? Look here.
Tape the holding string down to a flat surface to make your weaving easier.
Starting with the strip furthest to the right, weave over, under, over, under until you reach the end. Pull tight.
Continue weaving, always working with the strip furthest to the right. This "working strip" will always take the place of the cord furthest to the left, so be sure to incorporate it in the weaving process.
Pull tight each time you reach the end and use your fingers or a pencil tip to keep the weaving even until you reach the desired length.