https://fhetextbook.github.io/ which i believe was linked on this website previous is what i used to learn about how this stuff works.
Also this lecture by Vinod Vaikuntanathan is really helpful if you want to learn about FHE: https://www.youtube.com/watch?v=5LGwaICJ5sw
Also this lecture by Vinod Vaikuntanathan is really helpful if you want to learn about FHE: https://www.youtube.com/watch?v=5LGwaICJ5sw