To add an event to your timeline, simply click Add Event in SmartPanel.

Once you have added an event, click on it to select it, or select several (How?).
Then, change the date, connector style, event shape, and whether the event attaches at the top or bottom of the timeline using those respective controls in the Events group of SmartPanel.

While the event is selected, you can add text to it simply by typing.
You can remove an event by selecting it and clicking Remove Event in SmartPanel. Or select it and press the Delete key.