^^I highly disagree. Not to mention that's just another thing to think about and to more than likely mess up. We have relatively low speed autocrosses here, and running a course switching back between first and second is a waste of time. Like Carrera said, there is rarely a case where you'll ever need to go back to first gear, especially in the shorter geared non-SVT Foci (assuming you're driving a manual).
Assuming you have little competitive driving background, your driving skills are going to be below the car's abilities. There's really nothing the Focus can't do for you at this point that you can fully exploit from the car's capabilities. It's not a jab at you - just every case I have seen when it comes to a new driver, including myself.
Like everyone said, walk the course. It's easy to get confused your first time out with the sea of cones if you're unfamiliar with what they mean. Take it slowly going out there. You're not going to impress anyone or learn anything by trying to find and exceed the limits of your vehicle or your abilities on your first run (or first few runs). Simply try to look ahead, try to be smooth. I can't really add more to what's been said. You're going to have a blast no matter what!