If You already have a SSL certificate you can also use that, to enable SSL certificate you have to :-first of all Select Domain info in the Domain Settings menu and
then Click the Edit icon in the Web Service field.
Enable SSL for the domain in the list.
From One the page that appears, you need to choose the Import SSL certificate option in the SSL Support section.
Then you need to enter the SSL Server Private Key and SSL Certificate in the boxes that appear.
In the Site Name field, you need to choose whether you want to secure with or without the www prefix. In this, Only one option will work correctly. For instance, if you choose to secure http://www.domain.com, your visitors will get security warnings when they go to http://domain.com.
And in the final, Click on the Submit. and your site is secured.