Good day, I have a problem with my page, install my site in a VPS and add an SSL certificate and it works but before entering the message "SITE NOT SURE" someone knows what is due? my site is this
As far as I could see the certificate you are using is "self-signed", meaning it was not extended by a trusted CA.
Web browsers already come with a certificate from the main CAs and that's why when you enter a site, any installed certificate signed by one of these CAs is recognized and if there are no other problems it shows the green lock.
As the browsers do not have a certificate that matches the one you made, then they do not know the certificate of your site and they raise the alert.
To correct the problem you need to buy a certificate from a reliable CA. Or, if it's just for testing, you can make the browser make an exception and make it as valid. (The exception has to be given in each browser)
EDITION I: Look for Lets Encrypt, they extend free certificates with validity of 90 days.
As I saw you already have a ssl certificate, the important thing is to configure it well. Many will recommend us to use Lets Encrypt, but I recommend you use a "Comodo" certificate.
How all these certificates are registered depends on your virtual machine, so it is very difficult to tell you what you are doing wrong if you already bought one.