Update the repositories in Ubuntu

Open up your search for resources 

 

1. Type Terminal and click on the terminal icon.

2. Then type the following code in the terminal

 :~$ sudo apt-get update  

3. Then it'll prompt you to enter the administer password. Hit and enter.  

This will downloads the package lists from the repositories and "updates" them to get information on the newest versions of packages and their dependencies. It will do this for all repositories and PPAs. From http://linux.die.net/man/8/apt-get: