Installed dvd iso on a VM in Proxmox, after installation, can't open/enter GUI

[chliny2016]

After installation (as user 'installer'), see the 12 options, (I.e. option 6 is reboot, 0 is log out, 8 is shell). if i select 8, it goes to shell. Wonder how to enter the GUI interface. I tried to open a browser in shell, with commands like xdg-open, gnome-open, all say "command not found", I also try to run the commands in folder /usr/local/bin, same, 'command not found'. I even run this command `python -m webbrowser "http://www.example.com/"` in folder /usr/local/sbin, it succeeds, but nothing happens.
would you pls help.
Thanks.