Easily install an SSL certificate on your domain using AutoSSL.
In order to install an SSL onto your domain, you may use the WHM utility "Manage AutoSSL" which installs domain-validated SSL certificates for the Apache®, Dovecot®, Exim, Web Disk, and cPanel Server services for users’ domains. Here you may issue a run against all the users on your server, or you may choose to have AutoSSL validate and issue certificates for the domains on a single users' account.
In order to issue a check against all the domains on the system simply select the blue "Run AutoSSL For All Users" button.
More on AutoSSL may be read here.