This post is the simple answer to that question. IIS’s URL rewrite module can help us accomplish this as well as other rewrite tasks. For a complete look at how URL Rewriting works, take a look at the following MSDN article on URL Rewrite. Then look at the following as an example of what to add to your web.config:
<rewrite> <rules> <rule name="Redirect to HTTPS" stopProcessing="true"> <match url="(.*)" /> <conditions> <add input="{HTTPS}" pattern="^OFF$" /> </conditions> <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" /> </rule> </rules> </rewrite>