Sure thing, newbie! First off, let me say I'm thrilled to see such enthusiasm in a young cyclist. It's not every day I come across a 15-year-old with dreams as big as yours.
As for training, it's crucial to start small and gradually build up your endurance. You wouldn't want to burn out too quickly, would you? Try incorporating hills into your rides to build strength, and don't forget to mix in some high-intensity interval training. It's a game-changer, trust me.
Regarding diet, you'll want to focus on carbs for energy, lean proteins for muscle recovery, and healthy fats to keep you full. Stay hydrated, and avoid processed foods as much as possible.
As for gear, I'm stoked that you're getting a Trek for Christmas! It's a fantastic bike, and I'm sure you'll love it. Don't forget to invest in some quality cycling shorts and a helmet that fits well. Safety first, kiddo!
And finally, my advice for competing in an event by the end of the year: don't choke. Just kidding! (Sort of.) Embrace the nerves and use them to fuel your competitive spirit. And remember, win or lose, you're still a cycling rockstar in my book. Now go out there and show 'em what you've got!