Don't be scared; remember this is purely for fun and experience. Although there is a 90% chance you fail, since you're still new to both game jams and game development, either by failing to create a game or even submitting it at all (speaking from experience), you must continue working on games. A chef doesn't become a 5-star chef overnight; it comes through experience and dedication.
Since this is your first, I would like to give you 3 things to remember:
1. Create a small game, a really small game. If you think you can create a game in 10 hours, think of another that you can create in 5 hours or less. In most cases, a dozen features and game mechanics will not create a good game, only make it messy. Focus on a game with the simplest idea. If you're thinking of a platformer, remove the idea of moving platforms and swings. If you're thinking of a shooter, only create 1-2 enemy types. A polished small game is better than a big game that is not even fun at all.
2. If you don't really need it, DON'T implement it. You don't need the full blown audio settings and control settings, so remove them. You don't need a cool and fleshed out main menu; remove it. You don't need to add a credits menu, just do it in your game's description and remove it. Certain things that you can just write in the description of your game, you DO need to implement in your game. It will only take a lot of your time. Most games don't have a menu at all, just "press any key to start the game".
3. Do not polish your game early on. Embrace the fact that your game will look bad at the beginning, so focus on the main mechanics first before polishing your game. You don't need to squash and stretch in your prototype; do it after so that even if you haven't polished your game on time, the main mechanics and fun are still there.
Remember that your life doesn't depend on the game jam; if you need to rest, then rest. If you're hungry, then eat. This is just for fun and experience, so don't be discouraged whenever you don't win or even come close to winning. It's still an experience worth your time, so look at the criticisms of your game and strive to make a better game next time. Remember that you don't get good over night, over a week, or over a month. It's a process, and it will only pay off if you have the perseverance to continue doing it. That's it, and good luck on your first game jam!