(Note: this applies to a shared hosting account with a Plesk v10 or v11 control panel interface)
First, generate a new (or renewal) CSR. Login to your account's control panel, go to Websites & Domains -> Secure Your Sites -> Add SSL Certificate. (If you are setting up SSL on this domain for the first time this option may not be available. Contact our support department in order to be assigned a dedicated IP address.)
Fill out the sections "Certificate" and "Settings". Click "Request".
A new SSL entry should now be listed. Click on it in order to view the CSR.
Go to http://www.sectorlink.com and purchase a new certificate. During this process, you will be asked for your CSR. Copy/paste this in from your control panel interface.
Once your SSL order has been processed by our support staff, you will receive a confirmation email (usually at the WHOIS admin contact address for the domain in question). Follow the instructions provided in the email in order to proceed.
Once completed, you will receive an email with your new SSL certificate. Go back to the new SSL entry in your control panel (under Secure Your Sites) and copy/paste the Certificate and CA (Intermediate) certificate in the appropriate fields. Click "Send Text".
Go to Websites & Domains -> domainname.com (at the bottom of the page). Check "Enable SSL support". You may be given a drop-down box with a list of your certificates -- select the appropriate one and save settings.
