Is it just an exhibition? Do you have to make weight? If it's just for shits and giggles, don't worry too much about it. If your coach has any good sense, he'll pair you up with another guy with no experience.
If you don't have to make weight - good, you won't develop an eating disorder (yet)
If you do, lose the weight SLOWLY, and don't wait to the last day to dehydrate yourself for 10-20lbs like a moron. That is what people who get paid for this shit do, don't sacrifice your long-term physical and mental health for a stupid amateur fight. Eat lots of veggies, cut down on starches, breads, and of course sweets, drink some water w/ potassium chloride and salt in it to keep electrolytes up, don't eat junk/processed shit (if you do, and cut it all out at once, expect to feel like utter shit) try to get in lots of protein, if you struggle with that just use whey. Once you fight, keep eating clean afterwards, do not eat like shit and balloon up in weight.
Eat around 4 hours before the fight, preferably something like steak, don't eat something super glycemic like pasta because you'll get an insulin crash like a motherfucker. It's best to fight (and train) on an empty stomach so that nothing will be sloshing around in you when you fight.
General training tips:
Don't be a hero. Protect your head.
Lifting heavy weight will NOT make you big and bulky. If anyone from your gym tells you otherwise, they are an idiot. Read Starting Strength, or one of Pavel Tsatsouline's books. If you do weights correctly, and with proper form, they will make you more explosive, and more powerful.
Running is good, but you get plenty of aerobic work from training in general. If you want to get in extra work outside of the gym, do hill sprints, kettlebell circuits, sled-pulls if you are feeling frisky, etc.
Hit pads, listen to your coach, ask questions (NO SUCH THING AS A DUMB QUESTION), listen to your body.
Good luck, have fun.