Help me to install an SSL certificate, my service is with Hostgator

Probably switch to another hosting provider.

If I read this from Hostgater correctly: How Do I Use the Third-Party SSL Certificate I Purchased?, it basicly comes down to this:

  • Elaborate procedures due to difficulties at Hostgator to get a certificate from Let's Encrypt (cóuld be very easy, but they decided to make it difficult);
  • Pay Hostgator a fee at a minimum of $ 10,- (for a single domain) to install the certificate.

See Web Hosting who support Lets Encrypt for a list of (un)supported hosting providers. You can find Hostgator in the "Waiting/Delayed" section.