By default, Ubuntu does not show Computer,home,network and Trash icon on the desktop in Ubuntu. Instead Ubuntu shows the Trash icon on the extreme right of the bottom panel. Also having the Trash icon on the desktop in Ubuntu is a good option, because it becomes easier to drag - drop files onto the Trash icon.
A Computer icon on your desktop gives you easy access to all mounted drives and your home folder at one place just like Windows does. Here is how you can show the Computer,home,network and Trash icon on your Ubuntu Desktop.
Press Alt + F2 and type gconf-editor in the dialog box and Click Run to start the GNOME Configuration Editor.