If you go to the "My Account" page ot try to checkout after adding a product to your cart and see the below text or pages in your respective browsers:
MOZILLA FIREFOX:
This Connection is Untrusted
You have asked Firefox to connect securely to www.yourdomain.com, but we can't confirm that your connection is secure.
Normally, when you try to connect securely, sites will present trusted identification to prove that you are going to the right place. However, this site's identity can't be verified.
INTERNET EXPLORER:
There is a problem with this website's security certificate.
The security certificate presented by this website was issued for a different website's address.
Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server.
SAFARI:
(Popup) Safari can't verify the identity of the website "www.yourdomain.com".
The certificate for this website is invalid....
OPERA WEB BROWSER:
The server's certificate did not match its hostname. Accept?
OR
Unable to complete secure transaction
GOOGLE CHROME:
This is probably not the site you are looking for!
You attempted to reach www.yourdomain.com, but instead you actually reached a server identifying itself as otherdomain.com. This may be caused by a misconfiguration on the server or by something more serious. An attacker on your network could be trying to get you to visit a fake (and potentially harmful) version of www.domain.com. You should not proceed.
These errors simply mean you probably do not have a purchased SSL certificate, and the Shop Secure URL in the Settings area of your Administration Panel is defined to https://www.yourdomain.com/. The secure version of your domain's URL will only work if you have purchased an SSL certificate and have it installed to the server.
With a fresh installation of SunShop, the software assumes you have such a secure URL. To use the non-secure server until you do obtain an SSL, please go to your admin panel and login, then navigate to "Settings" at the header, and change the "Shop Secure URL" field to remove the "s" in https. Save your changes. When you do obtain an SSL and https://www.yourdomain.com/ works, replace the s in the URL.
Your host's Shared SSL can also be used as your secure server. If you decide to do this, change the Shop Secure URL field to the host's shared SSL URL. Because you likely have had your key already generated and assigned to the domain name, please create a ticket to Support at https://my.twt-inc.com/submitticket.php so we may update your key with the new shared SSL's URL. Please ensure your license is NOT expired before requesting this change.