World of "www"

This is a very simple question, but for beginners it is little bit difficult,
Now assuming that everything is installed, open the httpd conf file and start editing it,

You can find this file in
/etc/httpd/conf/httpd.conf

or directly edit it

vi /etc/httpd/conf/httpd.conf

 in this file search for Directory "/var/www/html" this can be on line 290-320
You will find a line of code, just like below

AllowOveride None

Just change it to

AllowOverideAll

Save it, and exit, mod_rewrite is enabled on your server
:)