To include advertisement in your Windows 8 Apps (including the phone apps) see the article at:

http://msdn.microsoft.com/en-US/library/hh506371%28v=msads.10%29.aspx

For the walkthrough on using Advertisements in your HTML5/JavaScript Based apps (including Scirra Apps):

http://msdn.microsoft.com/en-US/library/hh506343(v=msads.10).aspx

Make sure to add error handling to your app where possible.