Default logon credentials used to access the SharePoint server can be configured in Site Manager -> Settings -> Microsoft SharePoint. If you configure a Username and Password here, it will be used by default if you leave the Username and Password fields blank in web part properties of the SharePoint web parts.
If you enable the Use Windows Authentication option, the current user's windows domain credentials will be used to access the SharePoint server.
The address of the SharePoint server itself needs to be specified in properties of the SharePoint web parts.
Page url: http://devnet.kentico.com/docs/devguide/index.html?sharepoint_settings.htm