I have made the long tail (tag end) red so you can follow the next step.
Put the tag end back through the front of the loop and do another four turns up the inside of the loop following the lay of the original four twists.
To tighten as a loop put your fingers in the loop the swivel is shown on, and pull the knot up slowly.
If any of the loops jump ot of place give the tag end a light pull.
Rotating the hand you are using to hold the loop open while setting the knot will make it set much more eaisily.