To play a slideshow in Keynote, click on the Play button in the toolbar or click on Play Slideshow after accessing the Play option from the menu. After starting the slideshow, navigate through the slides by using the mouse or via the P and close bracket keys.
To modify the slideshow, select Preferences after clicking on Keynote, click on the Slideshow button in the new window, and make the desired modifications. With the Apple Keynote Remote app, you can use your iPhone or iPod Touch as a remote control device by selecting the Remote option in the Preferences window. You can suspend the slideshow and display a blank screen by pressing B or jump to the first and last slide by pressing the Home and End buttons, respectively.