Please note that crochet terms in US and UK are different. In US the stitch is called single crochet, however for British it`s double crochet.
1. Insert the hook into the next stitch.
2. Yarn over. Wrap the yarn around your crochet hook.
3. Pull the hook and working yarn through the loops. You should now have two loops on your hook.
4. Yarn over again.
5. Pull the yarn through both loops on the hook.
6. The single crochet is completed!