I agree with @tlink . Even if you want to learn pentesting Kali is not the good platform to start because it has config and software modified to suit a pentester who knows its way around the system. So to use kali in the first place you have to know how to use linux. Starting with a friendlier distribution and learning your way with the OS its the first thing you need to do. And when you become good enough you technically don't even need kali to do pentesting you can use ubuntu or something, its just that kali has a lot of stuff preconfigured so you don't have to spend a day setting it up
P.s. Also for resources on learning linux http://www.ee.surrey.ac.uk/Teaching/Unix/ I found this thing online I dont know how good it is. But my main suggestion would be a book.