There are two main ways to add a headline (chart/graph).
- The easiest way is to double click on the title and edit the text in the window that opens up.
- If you do not see a title to double-click on, you can edit the title under the chart's presentation properties.
- Click anywhere on the white area around the chart.
- Open the presentation properties tab.
- Click on "Edit" next to "Main title" in the chart elements group.
Under 'Main title' there's edit button for a 'Subtitle' element if you wish to add it.
When editing the title, as with any text element, you can add a dynamic text.
Find more information on dynamic text here: Dynamic Text