How do you make a double box spiral out of gimp?

To make a double box spiral out of gimp, you first need to take 3 strings of any colors, one of which is 1 and a half times the other two's length. (You can make a rough guess.) Then, find the middle of all three strings. Take the longer one and make it so that it faces you vertically, leaving the other two side by side facing horizontally laying on top of the longer one. If you know how to make a box, skip these next instructions. If not, to make a box you have to make a loop out of one strand, so it goes straight across next to the other strand of the same color, which you will then make into another loop. Repeat this process with another 2 loops of the same color. When you