How do I reserve a Marriott Resale Timeshare

I am contemplating buying a Marriot Resale timeshare. I am already a Marriott Owner. If I buy a week on a resale, do I still book my time through Marriott Vacation club or does it happen via an exchange in II? I'm new to this and would love your suggestions. Thanks!

Go to www.tugbbs.com as they have an entire Marriott forum with many knowledgable members that can answer any Marriott question you may have.