When first learning to crochet the whole process will feel very strange, as you will have to hold the hook, yarn and work all at the same time as you try to create the various crochet stitches. But work at it, practice the stitch until it feels natural, this will not take long. A great idea for practicing the basic stitches is to start making up a load of individual Granny squares (or one huge square) to get use to naturally and easily moving the hook. Also at the end you can sew them together and have a cozy blanket.
As you crochet, the yarn is guided through your fingers, this is what actually creates the tension of your work and therefore determines how tight, or not, your crochet stitching is!
If you look at a crochet hook you will see that it tapers inwards as it gets closer to the actual hook, therefore it has differing thicknesses. The further away from the hook itself the thicker it becomes. Therefore if you allow your loops to go up the shaft of the hook then your loops will be larger, and hence work will be looser. If you work near the hook itself, your loops will be smaller; and the smaller the loops the tighter the stitches. So if you find yourself working along the hook shaft and not near the hook, bring the loops down towards the hook and give the yarn another pull to tighten the loops, so that they decrease in size.