Log in to your Pi and install the Tight VNC Package
$ sudo apt-get install tightvncserver
Next Run TightVNC Server which will prompt you to enter a Password and an optional View Only Password
$ tightvncserver
Once that is done you can start a VNC server from the shell prompt. This example starts a session on VNC display zero (:0) with full HD resolution:
$ vncserver :0 -geometry 1920x1080 -depth 24