The E-R model consists of entities, relationships between or among entities, and the attributes of the entities. In order to create a detailed and fairly comprehensive E-R model, you will have to be clear about some of its relevant components, such as the entities, attributes, relationships, and the degree as well as the cardinality of a relationship.
Relationships are associations between the instances of one or more of the entities.
Degree of a Relationship is the number of entity types that participate in a relationship. The new entity diagram window titled ERD1 will appear if you select the ERD from the Repository Object Navigator. In this case just go to File and select New. After you select New, you should see Figure 5.3a. By this time, you should have a conceptual idea about the entities, the attributes and the relationships among the entities, that you would like to represent in the E-R diagram.