For this one I have chosen to make a simple 4 colour design so if its your first one it will be easy to master the knotting before moving on to more complicated designs.
What you need:
4x 28 inch strands of 1mm cotton cord (or embroidery thread)
A safety pin (or selotape)
A measuring tape
1: Cut 4 strands of whatever cord you are using in the colours you have chosen to about 28 inches each.
2: Leaving about a 3 inch tail tie a knot to secure all 4 strands together.
4: Bring the yellow strand behind the blue and back through the front.
5: Now holding the blue strand pull the yellow to tighten the knot all the way to the top.
6: Now repeat the process on the blue strand again so you now have a double yellow knot.
7: Repeat this whole process again on the purple and pink strands so you have now got yellow knots across the top and the yellow strand is now on the right and the blue strand is now your first strand on the left. It will take the first few rows to get the knots to sit straight so don't mind if they are slightly wobbly.
8: Now you need to start the process again knotting the blue strand all the way across.
9: Now continue this until you have the length you are looking for.
To finish this off you can just plat the loose strands on either end so that you can secure it around your wrist with a simple knot.