htaccess

[orbin]

Hey guys Howdy,
Recently i am trying to create CMS through php as front end and as a backend using mysql. Now i want to implement it through a server. But i have huge quries about (dot)htaccess. I want to know about this file concept. Is this a file authentication technique of apache server. I want to hidden one folder admin and the other i want to access public. When people view the site the automatically can show the public content. How do i do this?How to setup http server? Can any one tell the technical step? I can understand cause i have a CSE background.thank you.