Facebook is the largest online social networking site and currently has more than 1 billion users. Facebook allows people to interact, share photos and find people. In addition to using Facebook for social purposes, many people use it professionally for business networking.
More and more businesses with an online presence will link users to a Facebook page.
How to create facebook account
Beginners Guide to Facebook through this Video Tutorial
Useful info : http://mashable.com/2012/05/16/facebook-for-beginners/