picoCTF is a security game which is good start for beginners in security.
Just go to the website https://picoctf.com/ and register and you can know all the details about.
I prefer you to go to the basic viewer instead of the game as the game is a bit slow and you should not concentrate on the game, instead you can solve all the challenges in the basic viewer.
All the best go ahead and solve the sums.(fingers crossed)