How Do I Install Silverlight on a Mac?
Start by downloading the latest version Microsoft Silverlight plug in for your browser at http://www.microsoft.com/getsilverlight/Get-Started/Install/Default.aspx. Double-click on the Silverlight file to start the installation and follow the on-screen instructions to the end. Once you restart your browser you'll be good to go.
Click the button that says "install"
Very carefully, I should think.