First, I would like to welcome you to the amazing sport of MTB racing. Unlike other forms of racing, MTB racing is a relatively cheap form of racing when compared to other forms such as motocross /Supercross racing, or any type of auto racing where initial start up cost can be $5000 and up. A new mountain bike can be purchased for less than $2000 and a used bike is much cheaper. Being a racer myself I can remember how exciting and scary my 1st race was. I didn't really have any idea what I was doing other than riding my bike. Let's talk safety. Just because nobody in your class has a lot of safety equipment other than a helmet doesn't mean you don't need too wear it. Knee and elbow pads are a good idea especially for a new rider/racer. Most xc (cross country) racers wear a normal bike helmet, but while not required except in downhill racing full face helmet might give more confidence with extra protection. Now on to tires. I'm discussing tires because of what I've personally went through. A lot of guys I ride and race with have years more experience than I do and many of them are always talking about ground roll. The less aggressive your tire is the faster it will roll, but when you have less aggressive tires you take away control. My advice especially for new riders, have a more aggressive tread with lower pressure. 30 to 35 psi for most tubes tires. Tubeless will allow you to have an even lower pressure. Once in the trail you have to push yourself to go fast, but always be realistic in your personal skill level. If there is a drop off you know is out of your skill set walk it or go around if the trail allows. With enough practice what once was out of your ability will become second nature. Last, just remember if your not having fun it's not worth doing so make it fun for YOU. Thanks and we can't wait to see you at the races.