Open up your terminal (ctrl+alt+t) and enter this command.
enter your password and now you are root user! Notice the $ prompt has changed to #.
aman@vostro:~$ sudo su [sudo] password for aman: root@vostro:/home/aman#
Now, you don't need to use sudo anymore. for eg. now simply use apt-get update instead of sudo apt-get update.
You must be very cautious being a root user.
To come back to your normal $ prompt hit ctrl+d.