There is a script which you can use to easy install an openvpn server.

• openvpn-install-master.zip
• https://github.com/Nyr/openvpn-install

Here is how to use the config in the network-manager: convert_openvpn_ovpn_files_for_use_in_network_manager_chrisjrob.pdf

And here how to config an static IP:

• how_to_set_a_static_ip_in_openvpn_business_entrepreneurship_-_azcentral.pdf
• openvpn_set_a_static_ip_address_for_a_client_michls_tech_blog.pdf

Still I only added this:

ifconfig-push 10.8.0.100 255.255.255.0

Remind that: You need to enable the TUN/TAP and the PPP on your server. This is from RamNode configuration panel: