it is quite difficult to understand,,,and provided file is also little changed from video

Hi aankit8298 ,

We are currently working on the updated version of this course (should be out next month)

If you want to understand the principals on animations and actually learn more about character animation, try https://cgcookie.com/course/animation-bootcamp

It is still the older version of Blender, but all the principals remain the same, only the UI has changed and some of the buttons are different. (but not too many).

Make sure you post your work and I will review it.  And if you get stuck, just ask a question.