To have text appear when to click on an object you would need to send the text behind an item and it would appear as you clicked it.
To this place an item on the flipchart and the test. Then move the text over the object and go into design mode (click the little blue box in the top left corner) and and simply click the icon with the square in front of the tree. This will send the text to the back and the next time you click the object the text will appear.
If you need any further support please do not hesitate to contact us.