This is how to make sliding knots for an adjustable cord necklace.
1. Cut about 70 or 80 cm of cord
2. Put one end of the cord through the holes in the pendant and/or beads.
3. Take one end of the cord and tie it - around the other end - to itself. The knot is a simple over and under, pulled tight. The knot should slide, if it doesn't then you have tied one end to the other end and not to itself.
4. Now take the spare end of the cord and tie it around the necklace (which should now be in a circle). Again make sure you tie it to itself so that it slides.
5. Now you should be able to slide the knots to and fro to make the necklace shorter and longer.
6. Practice a few times and eventually it will become second nature.