Where can I learn about Tableau..?

Tableau Official web site is a good resouce for learning Tableau. 

You can find free E-Learn videos and comunities.

You can register also for onsile  or online courses.

Tableau community is the best to learn tableau.

Lynda.com has a course on Tableau.

check it if that useful to you.

Tableau has a big community where people share their learnings. You can join the tableau community to watch tutorials and tableau public where you can see and download visulisations done by other people.

find the offical tutorials on https://www.tableau.com/learn/training

There are a lot of courses out there. But my favorite ones are:

https://www.udemy.com/tableau10/

https://www.udemy.com/tableau10-advanced/

You can use the e-learning websites like Coursera, Udemy etc

Best place to learn the basic of Tableau:

https://www.tableau.com/learn/tutorials/on-demand/getting-started

Tableau's official website has it's own sets of tutorials that comes for free. you can also find other sources on youtube to learn certain special features that tableau has to offer.