Click on the Self-Message link 
button on the diagram toolbar.
Click on the object's lifeline at the point where you want
the message to appear.
This section provides techniques for refining your sequence diagrams. For information on collaboration diagrams, see Refining Collaboration Diagrams.
Together allows you to quickly convert between sequence and collaboration diagrams. However, whenever you create a new diagram, you must specify that it is either a sequence or collaboration diagram, and Together tracks it as such. The diagram displays in the UML Explorer and UML Navigator as the type of origin, and opens in that view. For example, if you create a sequence diagram, it will always display in the UML Explorer and UML Navigator and open in the Diagram view as a sequence diagram. However, you can view it as a collaboration diagram.
To convert between sequence and collaboration diagrams:
Right click on the diagram background.
From the context menu, select Show as Collaboration.
Repeat this process to toggle between the two diagrams.
NB: You may also switch between diagrams using the context menu for the diagram in the UML Explorer or UML Navigator.
To create a message from an object back to itself:
Click on the Self-Message link
button on the diagram toolbar.
Click on the object's lifeline at the point where you want
the message to appear.
To manually draw a return link, use the sequence diagram toolbar. However, to avoid having to draw a default return link, use the Properties view to create a default return link for you.
To specify a default return link:
Select the message link on the sequence diagram. The Properties view displays the associated link's properties.
NB: If the Properties view is not open, right click on the link, and select Properties from the context menu.
In the Properties view, select the return message field. By default, this field displays false.
To display a default return link, click the drop-down arrow for the return message field, and select true.
Objects display with a default lifeline when placed on the diagram. Their tops align vertically. If you draw a message link to an object and then check the creation type of the message, the created object will move downward to show that it exists at a point later in time from its creator.
To set the creation type for a message link:
Right click on the link.
Select Type > Creation from the context menu.
By default, message links are drawn on the diagram horizontally. This indicates the duration required to send the message is atomic, which means, that nothing else can happen during the message transaction. If the message link requires some time to arrive, during which something else can occur, then designate the message link as non-atomic using the Non-atomic delivery command.
To designate a message link as non-atomic:
Right click on the link.
Select Non-atomic Delivery from the context menu.
You can change a message location by dragging and dropping the activation bar. You can also select and drag message links up and down the object lifeline to reorder them. Reordering automatically updates the message link sequence numbers.
Sometimes you may wish to reorder message links keeping their sequential order and freeing the space between for new links. To do this, select a message link line, and drag it. This shifts all succeeding links. If you select multiple message links (pressing the CTRL key), then the links selected are moved keeping their increments.
Alternatively, use the sequence number property of a link (via the Properties view) to reorder message links.
Moving a creation message below a second message pointing to the same object removes the creation type from the message. Moving a destruction message above another message pointing to the same object removes the destruction type from the message.
You can lengthen or shorten object lifelines as needed by dragging the horizontal line of the bottom-most message link upward or downward. You can also arrange the position of other intervening messages this way.
You can reorder a sequence diagram and maintain any message links already created between objects. Select any Object, and drag it to the desired position. Such change is performed across the X-axis of Objects. You cannot move Objects vertically along the Y-axis except as described in "Adjusting the Size of Object Lifelines" above.
Together indicates the destruction of a created object by rendering a bold X on a diagram.
To set the destruction type for a message link:
Right click on the link.
Select Type > Destruction from the context menu.
You can nest messages by originating message links from an activation icon. The nested message inherits the numbering of the parent message. For example, if the parent message has the sequence number 1, its nested message has a sequence number 1.1.
It is also possible to create message links back to the parent activation, as shown in the figure below:
You can specify the following properties for message links:
To specify the properties of a message link:
Select a message link on the sequence diagram.
Right click on the link, and select Properties from the context menu.
In the Properties view, enter the required values.
To learn more about properties of message links, refer to the UML 1.4 specification.