Q. What is Copyleft means
A. Copyleft is a play on the word copyright to describe the practice of using copyright law to offer the right to distribute copies and modified versions of a work and requiring that the same rights be preserved in modified versions of the work.....(read more here )
http://en.wikipedia.org/wiki/Copyleft
Q. Where I will get more information about Free Software Foundation
A. http://www.fsf.org/
http://fsf.org.in/
You can read this book, if you want to know more about FSF history
http://oreilly.com/openbook/freedom/
Q. Where I will get Opensource application for windows
A. http://www.opensourcewindows.org/
Q. Why you say linux is better
A. Refer this web...you may find out
http://www.whylinuxisbetter.net/