See a previous years post for info
If your thinking of trying this out this year, can I recommend trying out a few questions from previous years to get yourself warmed up 
This is a link to last years for instance
https://adventofcode.com/2022
my school blocked it as a shopping website 
lol oof at least im lucky my friend showed me an exploit to bypass it (cannot share)
I just host my own proxy server on a Raspberry Pi. (My school blocks this forum otherwise.)