How do I implement Marketing Cloud Visitor ID Service?
Before implementing Adobe Marketing Cloud ID Service, walk through the step-by-step guide here http://adobemcidplan.businesscatalyst.com/. This guide will walk you through the steps that need to be completed prior to implementing the ID Service. One the pre-requisites have been completed, instructions for implementing are available in the Product Documentation here https://marketing.adobe.com/resources/help/en_US/mcvid/.
For more information on what the Marketing Cloud is, check out this video: