What do i need to learn + which OS to start with Linux ?

Hello,

i've been looking at Linux from far for years now, without ever using it because of how complicated it is and how much time it would take me to get into it.

But now that i know a bit more about programming, i want to learn and understand Linux.

So i have 2 questions :

- What do i need to know before starting with Linux ? Do i need to know some C if i really want to have fun with it ?
- Which one do i chose ? By name i only know Gnome, Arch, Debian and Kali. I have no clue which one is best, how do you chose which OS to start with ?