Make your slip knot and put it on the hook. Wrap the yarn around the hook and pull it through. You have made one Chain Stitch. Make ten Chain Stitches. Now, put the hook through the second Chain Stitch from the hook. Wrap the yarn around the hook and pull it through the Chain Stitch. Wrap the yarn around the hook and pull it through both loops on your hook. You have made one Single Crochet Stitch. Make one Single Crochet in each Chain Stich until you get to the end of the Chain. When you have made the last Single Crochet in the last Chain Stitch wrap the yarn around your hook and pull it through the loop on the hook. Now turn your work around.
There are two loops on top of your first row of Single Crochet. When you make your next row of Single Crochet you put the hook through BOTH loops. If you only put it through one loop all across the row you will have a line running through it.
Practice the Single Crochet Stitch. I will post How to do Double Crochet soon.