French knots! You either love them or hate them, personally I am a bit of a lover of them and as a result do like to add them to pretty much all of my embroidery. They seem so difficult and then once you've got the hang of them they're addictive. I am going to attempt a tutorial here, I'm sorry in advance if it's not clear enough but my computer literate/film maker son is willing to make a short film for me when he has the time (moving into video tutorials!!!). For now here it is in photo form.
You'll need both hands for this so rest the hoop on your knee or table
first pull your thread through to the front of your fabric making sure it is taut
wrap the thread around the needle
push the needle back through the fabric very close to where you came out (but not the same place or you might end up with a disappeared knot!). Keep the loose thread taut with your free hand (but not so taut you can't push your needle through)
let go of the thread and let the last of the thread through and hopefully you will have a lovely french knot.
If this is confusing I will hopefully soon have my very own film although I may film my daughter's beautifully manicured young hands doing the work!
If you're loving french knots then the incredible stitcher Karen Ruane has a flickr group specially dedicated to precisely this over here. I recommend a visit
Hope this helps