Applying a Composed Look programmatically

Applying a theme has change from SP2010 to SP2013, here is a link to the method to apply a composed look.

SPWeb.ApplyTheme(
	string colorPaletteUrl,
	string fontSchemeUrl,
	string backgroundImageUrl,
	bool shareGenerated)

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spweb.applytheme.aspx