From the control panel dashboard, look towards the bottom for "security settings", you will see "SSL/TLS Certificates".
Choose "Install free basic certificate with Let's Encrypt"
Select these options:
- Secure the domain name
- Include "www" subdomain for the domain and each selected alias
- Secure webmail on this domain
- Assign the certificate to the mail domain
If you do not have mail included on your server, you can skip the last two.
Click save and wait for it to say it's completed.
Note for CloudFlare users: If you keep getting a "too many redirects" error change SSL TLS settings in Cloudflare to "full" instead of "flexible".
- Login to Cloudflare
- Select your domain
- Click "SSL/TLS" from the left menu
- Click "Full"