In a Classifier Role shape, the object's designator string is underlined to indicate that the object is an instance. You can also include the object name before the colon.
Links, or AssociationRole, indicate relationships and, with arrowheads, can also indicate navigability.
Double-click a link, then click Message to define a message that flows along a link. Number procedure messages in accordance with call nesting.
The first message always comes from outside the context you are including in the diagram.