Connect to active session into the Raspbian

Enter root mode:

sudo su

Update system:

apt-get update -y && apt-get upgrade -y

Install x11vnc server:

apt-get install x11vnc -y

Configure password for VNC server:

sudo x11vnc -storepasswd /etc/x11vnc.pass

Create startup service:

cat > /etc/init.d/x11vnc << EOF
#!/bin/sh
case "\$1" in
start)
/usr/bin/x11vnc -xkb -auth /var/run/lightdm/root/:0 -noxrecord -noxfixes -noxdamage -ncache 10 -rfbauth /etc/x11vnc.pass -forever -bg -rfbport 5900 -o /var/log/x11vnc.log
echo "x11vnc Started"
;;
stop)
pkill x11vnc
echo "x11vnc Terminated"
;;
*)
echo "Usage: /etc/init.d/x11vnc {start|stop}"
exit 1
;;
esac
EOF

Set file executable:

chmod 755 /etc/init.d/x11vnc

Update startup situation:

update-rc.d x11vnc defaults

Reboot or start VNC server immediately:

/etc/init.d/x11vnc start

Now you can use TightVNC viewer to connect to your raspberry pi IP address.
For example 192.168.88.90:0