Do you remember when you first started learning how to crochet in the round, and you got that first row done, and there was a big hole in the middle? And then you just stared at it, thinking, "what am I supposed to do about that?!" And you got so frustrated that you stabbed your crochet hook through it and threw the whole thing across the room and gave up on crocheting for 15 years.
...For those of you still with me, there are three (as far as I've discovered) answers to this problem. You should grow to feel comfortable with at least ONE of them, so you NEVER EVER encounter the "hole" problem again. (Your family members and pets within throwing distance will thank me.)
1. The first way is to disreguard however many chain's a pattern tells you to start with, and just chain 2 (3 if you're doing half doubles or double crochets). Then you cram all the stitches the pattern tells you to start with into that first chain loop. It might be difficult, and it might twist your wrist a bit, but those stitches won't be able to budge.
2. The second way, again, is to disreguard however many chains the pattern tells you to do. Chain a comfortable amount, maybe 4 or 5, and then join them. Chain 1 or 2 more depending on which stitch you're doing. Crochet however many stitches you need to into that ring, BUT, hold the tail against the ring so that you're crocheting over the ring AND the tail. When you've got all your stitches in the ring, pull the tail, and like magic, the hole disappears.
3. This method confuses me unless I have the instructions right in front of me, but I know a lot of people swear by it. It's called "the magic ring." There's an absolutely wonderful, illustrated tutorial right here: http://www.crochetme.com/Dec_Jan_0405/reads_round.html
And there you have it, ladies and gentlemen. There is no reason you should ever have holes ever again.