I managed to setup openvpn connection, which works via terminal:
sudo openvpn --config '/home/deckoff/Desktop/vpn/config.ovpn'
This is usernmae/password login, I have ca.crt and config.ovpn files. I have installed the network-manager plugin, added the ca.crt location. When I connect, I am informe, that I have connected successfully, but I have no internet access... I suppose that I have to add the correct config.ovpn in the network manager plugin. I cannot see where to config the hostname/IP settings in the dialog Here is how my dialog looks like, I have deleted the gateway and username entries
this is the content of the config.ovpn file
client dev tun proto udp remote 188.8.131.52 1194 resolv-retry infinite nobind persist-key persist-tun ca '/home/deckoff/Desktop/vpn/ca.crt' auth-user-pass comp-lzo verb 3