There's a man page, but all you need to connect, once you've installed openvpn, is a simple command. Say you're in the directory containing the ovpn file. You would just do
sudo openvpn myovpnfile.ovpn
You do need to use sudo (or doas) to run it. I run the vpn I use to connect to work in a tmux session, so it doesn't take up a window with a little shell script
cd <ovpn_directory>
tmux new-session 'sudo openvpn myovpnfile.ovpn'
You can add a file into that directory called, e.g., creds
then in the ovpn file, you can add
auth-user-pass creds
to avoid always having to type your user name.
Depending upon the security of your machine, the creds file
can just contain the username, or username and password if you're confident of the machine's security. (I wouldn't put it say, on a laptop that could be stolen).
The creds file would just read
myusername
mypassword
All of this is stuff you can decide if you want to do. The only necessary thing is that you need sudo or doas to run openvpn (as it creates a tun interface) and the command has to give the path to the ovpn file.
