Start by looking at a Use Case scenario.

Break down the scenario into separate pieces.

A collaboration diagram consists of a set of objects that together carry out a scenario, the links between the objects, and details concerning the messages sent and received. A collaboration diagram can be drawn at the class level or at the instance level.

• At the class level, it shows the associations or relationships between the different classes.
  
  
• At the instance level, it shows the links or messages that are passed between the instances.

The business analyst may create a collaboration diagram to explore the following questions:

• What objects are included in the scenario?
• What messages are sent and received?
• What is the sequence of the messages?

Understand the type of collaboration.

Identify Object Instances Versus Object Classes

The objects appearing in a collaboration diagram may represent object instances or object classes. The way in which an object is identified determines if the object is an instance or a class. When the name is specified, it means this object represents a particular object instance. For example, John Smith:, the Applicant, represents the fact that  John Smith is a member of the Applicant's class. If no object name is specified, the object represents the class.