Hi, and Welcome to Zorin!
Well for starters you could install Ubuntu Tweak (download it from here:
http://ubuntu-tweak.com/then install with gdebi - you may need to install this from the software center or via a terminal:
- Code:
sudo apt-get install gdebi
then right click the Ubuntu-Tweak.deb package and select 'Open with...' and choose Gdebi - after it has checked dependencies, click on the 'Install' button - it will report if everything went o.k.
Once installed, Launch it, go to the Tweaks tab and then explore 'themes'.
Also install the following packages from Synaptic: gnome-color-chooser and gtk-chtheme (and not tried this one - gtk-theme-config)
Hope this helps!