1 Select File > New Diagram. Select Entity Relation or IDEF1X from the displayed list of choices. or
2 In the explorer, right-click Diagrams. Select Entity Relation or IDEF1X from the displayed list of choices.
Enter the name of the diagram to be created, and then click OK.
Assigning the Diagram to a Project Model vs Subject Model.
Each ER diagram must either be a project-level model diagram or a subject area diagram assigned to a project model. You cannot leave the model name blank.
3 Indicate whether the diagram will be a subject area or a model diagram by toggling the appropriate radio button in the Diagram Status field. Subject area diagrams are part of a model. The Model diagram is an aggregate of all subject area diagrams in that Project Data Model.
4 Enter the name of the project data model in the Model field or click the Choices button and drag the name of an existing project model into the text box.
5 Select a DBMS Field popup type, and then click OK.