I use this stitch ALL the time. I use it for eyes, the comb on my small rooster pattern, the middle of my daisies. There are so many uses for this lovely stitch. It's an awkward little monster to master for some, I still, after all these years of embroidery mess it up!
 

Bring your needle up through the fabric.
 

Now, hold the thread very taut with your other hand and wrap it around the end of your needle, keep it taut. You can wrap it twice or three times, the more wraps, the larger the french knot.
 

Very gently, pull the thread so that your wraps are tightened - while holding it taut, insert the tip of your needle right next to (NOT in the same hole) where your needle came up.
 

Then, bring the needle down through the fabric. As you do this, keep the thread in your other hand, tight. So that you don't pull the french knot through the fabric, pull this thread slowly and stop as soon as knot has formed.
 

I will be uploading a video to my youtube channel soon, as it's much easier to learn from watching others do it.
 

I told you it was a trickly little monster!