How do you know which vlans to add?

Hi,

I have the first lab workbook for routing and switching and on the first exercise it says to add the vlan's to the switches.  We are given a physical diagram and a layer 3 diagram but no layer 2 diagram.  So I understand that I have to create one myself but there is no explanation as to how you do this in the lab.  I've taken the CIERS class and they show you how to do this but it is a combination of looking at the layer 3 diagram and the layer 2 switching tasks which are not provided for this lab.  Can someone please explain what process the INE instructor is expecting us to follow in order to know which VLANs go where?