To install VNC just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command below.
sudo apt-get update
This updates the package list for apt.
Then you'll need to install the Gnome components using Software Center:
Or Using Terminal:
sudo apt-get install gnome-core
To install VNC server using Software Center:
Or Using Terminal:
sudo apt-get install vnc4server