If you are lazy to find everything on the internet (I was too, because there is just too much info and it's really hard to get just what is needed when you are totally beginner), go and buy 2D unity course in udemy, I started there. Last game jam was my first too, I felt very inexperienced but it went really well in the end! Good luck on your first game jam!
Unity Learn is free: https://unity.com/learn#explore-how-you-can-develop-your-skills
You can try starting with this one: https://learn.unity.com/course/getting-started-with-unity?utm_source=learn_recommendation
Yeah, I know. Just saying that it is the easiest way to learn without taking much efforts, because of how not easy it was to properly learn a least something for me, I gave up a lot of times, and this tutorial finally dragged me trough that! Not saying I learnt a lot but it was enough to create something and move on on myself! I think 10$ is not that much!