How do I add text to the top of a slide in keynote?

How do I add text to the top of a slide

Click the text box button in the button bar, then type in the text. One thats completed click on the background to deselect the box then click on the box to position it on the slide.

I am having trouble editing the top portion of a slide, how do I do this?

To edit the text, double click the text box, the text will highlight blue then retype.