The TTS On Demand service is primarily intended for use with iClone5, CrazyTalk 7 and CrazyTalk Animator. With these products you can simply add the MP3 to automatically create the lip-sync.If you are using CrazyTalk 7 and CrazyTalk Interactive Plugin you can then export your talking avatar and the included voice script which can then be added to your web page.
Please see HERE for video showcases and sample code.