To configure vnc and x server, you need to follow this instruction.
sudo apt update
sudo apt install xfce4 xfce4-goodies tightvncserver
vncserver
(Enter password)
vncserver -kill :1
nano ~/.vnc/xstartup
Remove all and paste this:
#!/bin/bash
xrdb $HOME/.Xresources
startxfce4 &
vncserver
Than you can connect with any VNC client like Real VNC to your server.
(Note that the port depends on your screen number, It will be 5900 + screen number. For example for the :1 screen port will be 5901)