Glad you had fun :]. Since you're a beginner don't worry about speed right away. Just get to know the pattern, and let your horse get to know it also. Go riding with others that barrel race so you can pick up tips and pointers from them also. There's lots of ways to run the pattern, just totally depends on you and your horses style. I have this book called Barrel Racing 101 by Marlene McRae and it's full of useful information. It's good for beginners. As for your seat, I'm still working on that one myself! My horse and I have a big problem with not sitting down properly around the barrels. I forget to plant my butt in the saddle which causes him to spin on his front end, causing me to fall off.
Anyways, I highly recommend getting that book. I got it on Amazon.com for somewhere between five and ten dollars I think. Don't worry about your speed until you and your horse know the pattern better. Good luck! :]