Use my existing SSL key and certificate?
To enable SSL, do the following:
Select Domain info in the Domain Settings menu.
Click the Edit icon in the Web Service field.
Enable SSL for the domain in the list. One the page that appears, scroll down to SSL Support and choose the option Import SSL certificate. Agree to charges, if any.
Enter the SSL Server Private Key and SSL Certificate in the boxes that appear: In the Site Name field, choose whether you want to secure with or without the www prefix. 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.
Now your site is secured.