Step 1: Cut and glue the ends of the cord
Put a small amount of glue on your fingertips, and twirl the cut ends of the cord back and forth to cover the first inch or so with glue. Let the ends dry before proceeding.
Gluing the ends works better than melting in this case, because the glue makes a short section of the cord stiff, and that makes it easier to weave the end in and out as you create the knot.
Step 2: Make the first two main loops
Now bring the long end over the loop you just made, forming a second loop (and a shape that looks kind of like a pretzel). The left loop of the pretzel will become the second main loop.
Step 3: Start weaving
Pull the cord almost all the way through, and stop when you still have a loop on the bottom. This loop becomes the third main loop.
Step 4: Make the fourth main loop
Pull the long end through until you have a loop left at the top. This becomes the fourth main loop.