The Matthew Walker Knot is an extremely stable way to create a knot at the end of your rope or to bring multiple ropes together to create a transition in rope craft. The 3-strand version of knot is very straightforward to tie. There is a multi-strand version of the knot that can be used to make this knot with any number of strands, but the process to do so is a bit fiddly.
This video shows you the 3-strand, then the multi-strand, demonstrating the knot for 4-strands, 5-strands, and 6-strands. Hopefully, the multiple demonstrations of greater and greater numbers of strands will help you master this very cool knot.
In this video, I am using 550 paracord in multiple colors instead of my usual hemp. This makes it much easier to see what is happening and how the various cords fall.