I am no expert, but since you said Urgent.. I guess you can view, add or remove certificates from your application servers administration console. It would help if you could be more specific, like which AS you are on etc., Hope this helps, Ashok.
Here's what I got from Verisign's FAQ: "How do Server Certificates work? 1.A customer contacts your site and accesses a secured URL: a page secured by a Server Certificate (indicated by a URL that begins with "https:" instead of just "http:" or by a message from the browser). 2.Your server responds, automatically sending the customer your site's digital certificate, which authenticates your site. 3.Your customer's web browser generates a unique "session key" to encrypt all communications with the site. 4.The user's browser encrypts the session key itself with the site's public key so only the site can read the session key. 5.A secure session is now established. It all takes only seconds and requires no action by the user. Depending on the browser, the user may see a key icon becoming whole or a padlock closing, indicating that the session is secure. "