When you install SiteEdit 2009, you are creating a new web site in IIS (on the same machine where your Tridion Content Manager is installed). This web site (often called the SiteEdit proxy web site) proxies incoming requests between your staging site and your Tridion server.
Browser
| (1)
SiteEdit
Proxy
(3) | (2)
+----+----+
| |
Tridion Staging
Content Web
Manager Site
So in the above diagram:
- you connect to the SiteEdit proxy web site (with a URL that identifies your web site, e.g. http://siteedit.mywebsite.com/default.aspx or http://staging.mywebsite.com:84/default.aspx)
- the proxy requests the corresponding page from the Staging web site (e.g. http://staging.mywebsite.com/default.aspx)
- the SiteEdit proxy parses the HTML and then contacts the Tridion Content Manager to get the necessary information about the Page and its editable Components.
This is a bit simplified (the actual process covers at least a dozen such steps IIRC), but it serves to illustrate the need to connect to a different web site when you are looking to edit content using SiteEdit 2009.