Take a length of rope in its midsection and wrap it around your non-dominant hand -- the left for right-handed individuals and vice versa for those left handed -- three times.
Reach under the lines in your palm and take the middle line. Pull this line toward the tips of your fingers, the pass it back over top of the other two lines, toward your forearm.
Pass the line that you have pulled toward your forearm under the two remaining lines and slowly remove the rope from your hand.
Pull the loop tight.