Login as root is seldom required. when installing new software, if you need root priviledge to finish the process (or if you need root from the start of the installation), use the su command (some people interpet the meaning of the name as 'switch user'; others 'super user').
It's a convenient way to have temporary root authority. Open a terminal windo, type wu, and press enter. At the next prompt, enter the root password. The prompt should change to show you are now root.
Run the command(s) you need, and when finished, type exit, and press enter to exit root priviledge.