Hello Mrudul

There are lots of online resources to help you getting started with tableau, including many video tutorials here:

Tableau Training and Tutorial

This website from the company I work for has a lot of useful links to blog posts etc.

https://www.interworks.com/en-gb/collections/tableau-training

And if you get stuck with a specific problem these forums are great for getting a solution from other Tableau users.

Hope that helps

Steve

This is also a good resource for workbooks and session recordings.

Virtual Tableau Conference Registration

Tableau opens up their past conference material for free online.  There you can watch hundreds of presentations.  Here is 2014's conference material:

Post-Conference Materials | Tableau Conference 2014

Watching the video and following along with the tableau workbook or the dataset they provide has been an enormous help in mastering Tableau.