The 'Performer' of a 'Use Case' construct can be assigned in the 'Use Case Diagram' via drag-and-drop. Both the “to-be” performed 'Use Case' and the 'Performer' constructs must be added to the diagram first before the performer can be assigned.

1. Within the 'Use Case Diagram,' select the 'Performer' which you would like to assign to a 'Use Case.'
2. Click the green circle and continue to hold down the left mouse button.
3. Drag the green circle over to the 'Use Case' of your choice.
4. When the parent 'Use Case' oval highlights green, release the left mouse button to add a performs/performed by relationship.
5. Once added to the diagram, the new relationship should appear as an arrow between the 'Performer' and 'Use Case' constructs.
6. Click the 'Save' button located on the toolbar to persist your changes to your project’s database.

* Note: The above process describes using the 'New' tab of the left sidebar, which automatically generates a new entity to represent each new diagram construct. If you would like to reuse existing entities from your database to represent a new construct, use the 'Existing' tab instead.

For more information on this construct and how it is represented in the database model, see Use Case Diagram Constructs.