Dialog msg-->then try again.You may need to reboot.installation will now abort... This script can not be ran with Administrative Privileges. The script elevates on its own. Please run the script with Standard User Privileges. Installation will now Abort. Help Me. (as root sh GUIInstall.sh) Help Me..
First I would be extremely careful here. You should not need to run a script, let alone with root privileges, to install a theme.
I understand, scripts such as this can seem "easy" if you are new to Themes, but, this is how social engineering works as well.
Here is a great tutorial on installing themes:
With that caution in mind, the error message seems to imply the script will elevate on it's own.
If you have a problem with that, I would ask you pastebin the entire script and paste a link back here so we can both look at what it is doing and if it need to be modified in some way.
EDIT: Added a snipit
First you need to be administrator for installation. login as administrator by using comand "sudo -s" and enter your password and then try again. I hope it will works.