In order to change or modify your site's default documents through IIS7 Manager, first connect to your site
1. Under the IIS area of the manager, double click on the "Default Document" icon.
2. Then click "Add."
3. Provide a name for the new document.
4. Your new entry will automatically be listed as the first document.
5. To to rearrange the order of documents, highlight one, then click the up or down arrows on the right panel, under "Actions".