It is very easy to add an SSL Certificate from the free Let's Encrypt Certificate Provider with GridPane. This will allow your site to be served by the encrypted HTTPS protocol, and your visitors will also benefit from the speed increased enabled by HTTP2 which only works via HTTPS.
Step 1. Go to the Sites Section of the GridPane Control Panel
Click on the sites link in the GridPane main menu to go to the Sites management page.
Step 2. Open the Site Customization Panel for your Active site
In the Active Sites panel, click on the domain in the URL column to open the Site Customization pop up box for the site you wish to update.
Step 3. Add a Let's Encrypt SSL Certificate to your site
Locate the SSL toggle in the list of site customizations available and click the toggle from Off to the On position
The toggle will turn to the green coloured on position and you will receive a green notification tell you that an SSL certificate has been successfully added.
Your site now has an SSL certificate and is being served by HTTPS.
Step 4. Check your WordPress site HTTPS connection
Type your site domain into your browser URL box using the HTTPS protocol to visit your site, for example.
You will now be accessing your site using the more secure protocol and benefit from HTTP2.
Step 5. Check HSTS (HTTP Strict Transport Security) is working
GridPane automatically configures your SSL certificate to enable HTTP Strict Transport Security (HSTS) to enable redirection of all HTTP traffic through HTTPS.
To test this is working you should also try to visit your site via HTTP, for example.
If HSTS is working you should be served this site by HTTPS still.