If you want to have a taste of the basics you should check out the OWASP juice shop, basically a game-ified insecure web application to poke holes into. It has tutorials, an achievement system and the different challenges all have a difficulty rating.
My cat loves people, especially people that are new, and a few months ago there were a bunch of construction workers in the house, the amount of surprised happiness I heard because my cat wanted to cuddle with the new humans, was really cute