This is the most difficult thing you will ever learn in crochet. I'm kidding, but when you analyze how crochet works, its all connected to the chain. Yarn over, pull up a loop. Is there any crochet stitch not involving that action? If there is, I don't know it.
So let's get to it. First you must start with a slipknot or other method of beginning.
With your working yarn in the back and your tail to the front, yarn over from the back, bringing the yarn up and over the top of the hook (hence yarn over).
Catch the yarn with the hook and pull through the slipknot.
That is your first chain. Remember that the loop on your hook never counts as a stitch. Continue with this method until you have the desired number of chains.
Now you have your row of chain stitches, what will you make of them?