[AntoniusBlock]

CTFs are a fun way to get started. Here are some that I like: Pwn.college, PicoCTF, and PortSwigger WebAcademy.

[fragmede]

http://microcorruption.com isn't a ctf but is a good one to play with

[veganjay]

Another good one: https://owasp.org/www-project-juice-shop/