The first thing that you’l need to do is download and install the UltraVNC application for the computer that you want people to be connecting to. It is available on the UltraVNC site. Look for a link "stable version" or similar. The file that I downloaded was UltraVNC-100-RC18-Setup.zip.
Unpack and install on the computer on which you’ll do the remote administering.
When you are installing it, you’ll be presented with a screen that asks if you want to "Register Ultr@VNC → Continue reading “Using UltraVNC for Remote Desktop Connection and Support”