As already reiterated to the boredom, staying logged as superuser all the time is a **very bad idea**. That said, it's your computer, your project, your choice, so I don't see why one should not share the information you asked, so...

Login with your normal user and from a prompt shell you can enter:

    sudo passwd root

this will allow you to enter a password for your root user. You can now logout and login again using your root user.