Take the rope end and fold it over to create a loop. Then wrap it back under and around the loop created.
Pull the tag end over and down to create a small loop at the base of the larger one.
Repeat this same action to create a second full loop at the base of the large one.
Pull the tag end of the rope down reasonably firmly. This will start to tighten the two small loops. Now tuck the tage end back through the 2 small loops and tighten the knot.