Database Diagrams?

Follow the steps:
 

1.  Open SSMS and connect to the database for which you want to create a diagram.
2. Expand the database in Object Explorer and navigate to the "Database Diagrams" folder.
3. Right-click the "Database Diagrams" folder and select "New Database Diagram".
4. In the "Add Table" dialog box, select the tables you want to include in the diagram and click "Add".
5. In the diagram, you can drag and drop tables to position them as you want. To create a relationship between two tables, click and drag the primary key column of one table to the foreign key column of the other table. A line will appear between the two tables indicating the relationship.
6. To edit the properties of a table or relationship, right-click it and select "Properties".
7. When you're finished creating the diagram, save it by clicking "Save" on the toolbar.

This is composed of entity types (people, places or things). It shows relationships that can exist between them. By defining the entities, their attributes and showing the relationships between them, an ER diagram illustrates the logical structure of databases