What is git hub and how to use it...???

Answer 1

Good question! I think you will find the answer here: https://goo.gl/Ye5XLi

Answer 2

Github is a social platform you connect with your Git software, so that you can host your Git repositories online, share them with your team (or the world, if open source).
If you use Git and not GitHub, then your repositories are just for yourself.
As an alternative to GitHub, you also have BitBucket, that does the same job (and some of paid Github features are free on BitBucket, such as private "me only" repositories).

Answer 3

https://try.github.io/levels/1/challenges/1