Enable Remote desktop in Ubuntu

Download Tightvnc from click here

1.Go to: System => Preferences => Remote Desktop
Check the boxes Allow other users to view your desktop and Allow other users to control your desktop, Also don't forget to set a desktop for security reasons.

2.Now you just need to know the ip-address your Ubuntu machine uses. To do this right click the icon with the two displays in your systray and click Connection information.

3.Now able to connect to your Ubuntu machine using a VNC client

4.If you want to connect to your PC outside your network you will need to know your routers outside ip-address and make a port forward in your router to your Ubuntu machine using port: 5900. You can use this website to obtain your outside ipaddress : whatismyip.com.

(Note : if you have a static ip no need of port forwarding)