In the IIS console, select the web application to be configured, e.g. "OWA"
Click the "Advanced Logon Settings" button.
To enable Single Sign-On by Auto-Post, tick the option "Auto Filling"
If the web application is one of the pre-configured server types such as OWA, then usually there is no need for any further configuration in this tab apart from ticking the "Auto Submit" option
Click "OK" to save settings