Wrap the nylon fret line over the top of the loop, and pass the tail through the loop as shown--Fig. 1.

Pull up on the tail end, and down on the loop end. Pull the crossing point under the wraps in the groove on the side of the neck--Fig. 2. 

 
Tie several half hitches knots, and place a little houshold glue on the knot--Fig. 3.