This documentation was tested on fresh installs of Ubuntu Desktop 18.04.1, 20.04 and 22.04.1.
Install the NetworkManager OpenVPN plugin if you don't have it. To do that, open Terminal and type:
sudo apt-get install network-manager-openvpn-gnome
Click on the Network icon in the status bar then “VPN” > “Connect” or “arethusa”.
Once connected, check your IP addresses.
The OpenVPN log is in /var/log/syslog , mixed with all other system logs. Skip until you see lines with openvpn.