The Address Book is basically where you store all of your customers. You can have 1 record for a particular customer and then have (for example) 5 vehicles that he has bought from you. All the sale records link to the 1 address record. Therefore, if the customer moves, you only have to edit their master record and the changes will be seen in the vehicle sale records.
Here is where you store their personal data. If the customer dies, you can check DECEASED to keep their name from bring printed in letters, labels, etc. You can also check if they are on the DO NOT CALL LIST so you don't get fined if you contact them. If they move out of state or if they are all deceased, you can uncheck ACTIVE CUSTOMER to make sure nothing gets sent to them.
VEHICLES keeps track of every car this particular person has bought from you. You can double click a vehicle and it will pull up the record of that sale.
CONTACT HISTORY shows a record of every contact you have made with that customer such as letters, phone calls, etc. Keep in mind, this can span over multiple vehicles.
SOLD FAMILY MEMBERS will show a list of everyone at their phone number (including themselves) who have bought a vehicle from you.
PROSPECT FAMILY MEMBERS shows everyone in the household that you have sold a vehicle to (including themselves.) Double click a name to pull up the record of the sale.