I suggest you take a look at the couple of materials that are posted on the Training & Support center. You can get to all the recorded training by logging into CRM On Demand, click the Training & Support link in the upper right corner, and then click "On Demand Marketing" on the main header of the home page (or search for On Demand Marketing in the search box).
There are some recorded TOI trainings on the Training & Support center that explain the account activation process and the integration.
There are many other training topics summarized on this page:
Also, the On Demand Marketing Config Guide has some sections near the end that explain how the initial sync happens and what steps need to occur before activating the sync process.