Ubuntu Linux runs the the desktop as a regular user account, and so all programs launched are launched in the context of a normal user account. To run a command-line program with superuser(root) priviledges, you normally will preceed the command with "sudo", as shown in this example:

sudo gedit filename.txt

Ubuntu provides a graphical alternative to the sudo command that you have probably seen if you try to run any administrative tool: You can easily and quickly run any program as root by preceeding the command with the "gksu" command. For instance, let's launch xterm as root by hitting Alt+F2 to bring up the quick run dialog:

We'll first see the password dialog shown above, enter your password... and there we go - we now have a terminal running as root:

Easy stuff!