I have gone through the book "Mastering Bitcoin" and I am not able to completely grasp it. I just need a break from reading and need to do something practical.
Is "
https://github.com/bitcoin/bitcoin/" is the original copy?
How should I read the source code?
Do I need to install some specific program /compilers for it
Technically you can find more technical source code on Github but I did not understand what actually you are looking to read on Mastering bitcoins book. If you want to learn the solidity coding normal Youtube videos are enough to do that.
Since you are newbie I do not believe that this is what you are looking for to learn now.
As a beginner you should check the article Rise and Rise of bitcoins this is the basic to learn for all the people.