1. You may need to lengthen the Lifeline elements to ease the placement of the Message elements. To lengthen the Lifelines, follow these steps:
a. Select the User Lifeline element.
b. Click the blue box at the bottom center and drag the box downward to lengthen the Lifeline.
c. Repeat steps a and b to lengthen the remaining Lifelines until your diagram resembles the following figure.