Pull your thread up through the fabric looping the thread off to your non-dominant hand (i.e. I'm right handed so I loop to the left) and bring the needle back pointing towards your looped thread.
(I am using 6 strands here just so it is easier to see what I'm doing.)
With your non dominant hand hold the thread and begin wrapping the thread around your needle while it pointing towards your non dominant. (Yes, this is a bit tricky at first. Be patient!)
(I'm obviously not holding the thread with my non dominant hand in this picture. The cat would snap this photo for me! ;) )
I wrapped only twice in this picture. You can wrap it as many times as you want, but honestly, I never wrap more than 5-6 times. The more you wrap, the larger the knot, but be careful with your tension on the thread in Step 4!
Continue holding the thread with your non dominant hand and carefully place the needle back into the fabric. Don't loose your wrapping around the needle. I put my index finger on the wrappings to help hold them in place. (If you do loose the wrapping, just go back to Step 2.)
Take care not to put the needle back in the same hole as where the thread initially came up through the fabric. If you do, your knot will pull through to the back of your fabric.
Pull the needle and extra thread through the fabric while holding an even tension with your non dominant hand.
VOILA! It is a French Knot!
Just to show you how the number of embroidery thread strands used can affect this stitch, take a look a this picture.
All of these knots were wrapped twice. The difference is that the knot on the left was done with a single thread and each subsequent knot has one more added strand with the knot on the far right being 6 strands.
My thread is twisting up on itself and making the wrapping difficult.
This happens when thread is being twisted while stitching. Simply hold your hoop upside down in the air and let the threaded needle dangle. It will untwist itself. Sometimes, you have to do this several times while working with certain stitches.
The knots have little loops of individual threads poking out!
Pay attention to your thread tension on your non dominant hand. It might be uneven as you pull the thread through.
I can't get the needle to go back through the fabric.
Your thread tension in your non dominant hand is too tight. Loosen up a bit.
Here are some examples of my work with French knots...
Mother Nature's Glory
Hand of Hamsa
A Sweet Tweet! - The heart in the center of the hoop is all knots
And this is the truth...
Pretty Little Posie