The first keyword is the type of file you wish to color, and the numeric argument is the color you want ls to show. Notice that the directory keyword has two numbers separated by a semicolon. The next number is the color, in this case 34 is blue. Optionally, you could add a second semicolon and specify a background color. You can also highlight files based on their extensions.
Many common extensions are already there.
If you want to add a new one, just insert a new line with the extension and the color. However, my hostname is localhost.localdomain . You can use the graphical netcfg tool provided by RedHat. To do this, open an xterm under X and su to root. Type netcfg , and you will see a hostname field.