I installed a VPN and started configuring my website to use the VPN addresses, but will that add a stronger layer of security for my website visitor's?
If your site uses a VPN, then the connection from your web server to the VPN server is encrypted. The connection between the visitor and the VPN server is not encrypted. The visitors do not get the benefit of the VPN end-to-end to your site.
Client -- Internet -- VPN Server ++ Web Server
If you use TLS, then the connection is encrypted end-to-end from client to web server. The VPN will not add any significant protections to the visitor.