Click the Aggregates Link button 
on the diagram toolbar.
Click the component or node source element.
Drag the link to the destination component or node element.
Drop when the destination element is highlighted.
An aggregation relationship denotes that one element contains one or more other elements. This kind of relationship on the deployment diagram can only drawn between nodes and components.
To create an aggregation link:
Click the Aggregates Link button
on the diagram toolbar.
Click the component or node source element.
Drag the link to the destination component or node element.
Drop when the destination element is highlighted.
Related Topics:
Creating Links
Moving Links
Editing Links