sudo gedit opens the familiar text editor,

open the file '/boot/grub/menu.lst'

save a copy as 'menu-bkp.lst' just in case

edit what you need, change the colours, default etc

save as '/boot/grub/menu.lst'

It's a file named menu.lst in /boot/grub. You must be root to make
changes and you can use any text editor, for example in the terminal
type sudo gedit /boot/grub/menu.lst .

Be sure to save a copy of the original first and don't make changes
until you have done you homework and understand how it works.

From your question I am guessing that like myself you are new to Ubuntu, but
as you do not seem to have received a response I will try to help with what
I have just been through.



I found that the easiest way to change the boot order and other basics, was
by using 'Startup manager'.



'StartUp-Manager' is accessed via System > Administration > StartUp-Manager.
If it is not in your menu, install it via synaptic System > Administration
> Synaptic Package Manager. StartUp-Manager is in the 'universe' repository.



If you really want to edit the grub menu then you need to open a terminal
and enter: gksu gedit /boot/grub/menu.lst

Open as root the menu.lst file located /boot/grub. Make the changes
and save. The changes will take place when you re-boot.