SSL enables browsers to communicate with a web-server over a secure channel that prevents eavesdropping, tampering and message forgery. You should always use SSL for login pages where users are entering usernames/passwords, as well as for all other sensitive pages on sites (for example: account pages that show financial or personal information).
具体步骤参阅以下文章：
http://blogs.msdn.com/bags/archive/2009/01/23/self-signed-certificates-on-iis-7-the-easy-way-and-the-most-effective-way.aspx