Check if Let’s Encrypt extension is visible in your Plesk panel. If it’s there, you can get a free SSL certificate for your domain name from Let’s Encrypt CA.

To get an SSL certificate:

1. Go to Websites & Domains section and then move to Let’s Encrypt.
2. Mention the email address which will be utilized for recovering lost key and urgent notices. Email address of subscription owner is used by default.
3. Mention if an alternative domain has to be included for the domain name and aliases that are selected. For example: www.znetlive.com for znetlive.com. We recommend that it should be turned on. 
4. If any domain aliases are there, select those that should be included in SSL/TLS certificate.
5. Click on Install to receive and deploy the Let’s Encrypt SSL certificate for your subscription.

Now when you’ve installed the certificate, you should use it for securing your site by following the steps below:

1. Go to Websites & Domains section and click on Hosting Settings.
2. Here, select checkbox of SSL/TLS support.
3. Select the certificate you’ve received from Let’s Encrypt from the Certificate menu and click on OK.