Crocheting in the Round is just like crocheting back and forth, exept you're going in circles. Chain five Chain Stitches. Put the hook in the first Chain Stitch, wrap the yarn around the hook and pull it through both loops on the hook. Chain one and turn. Now decide how you're going to start it. Are you going to crochet around the Chain Stitches or in them like usual? Crocheting around the chain stitches is when you put the hook completly under the Chain instead of in the loops.
Once you figure that out you start crocheting. Make however many stitches will fit on the circle or just crochet in the Chain Stitches. When you get to the first stitch you made put the hook through both loops of the first one, wrap the yarn around the hook and pull it through all of the loops on your hook. Chain one and turn. Now if you want the circle to be flat make two stitches in every stitch all the way around. If you want it to be bowl shaped like for a hat or bowl only increase in every other stitch of every other row.
Practice Crocheting in the Round. Look for How to Change Colors in Crochet.