In a collaboration diagram, double-click the Association Role shape to which you want to add a message.
Type a name for the association role, and then click Messages.
Click New. Type a name and sequence expression. Choose the stereotype, direction, and flow kind you want.
For a flat message or procedure call, click Properties. Select the operation you want the message to generate. If the operation doesn't exist, click New to create it.
For an asynchronous message, choose the signal you want the message to generate. If no reception for the signal exists on the classifier that the object lifeline receiving the message is based on, click New to create the reception.
Add a message to an association role in a collaboration diagram