You can turn on your PowerPoint slide show presentation either from menu commands or by using the icon on the editing screen. You can move back and forth through the presentation with the arrow keys. End the slide show with the Escape key.

Playing a presentation

Begin your PowerPoint slide show within the program. You can do this by double-clicking on the file icon, or by opening PowerPoint and choosing File, then Open from the menu at the top of the screen. From there, open the file by double-clicking it (if you have used it recently it may be in the Open Recent window). You will see the editing window for the presentation. To begin the slide show, click on the first slide in the left sidebar. Choose View from the menu bar at the top of the screen, then "Slide Show" to begin the presentation. The second way of beginning the slide show, which is a time saver, is to find the slide show icon, which is at the bottom of the editing window in the form of a small screen. Click on it to start the slide show from the current slide you are in. The Escape key gets you out of the slide show immediately. If you want to see the presentation sequentially, you can just click on your trackpad or mouse (if you are using one for your laptop) which will advance to the next slide. Once the presentation reaches the final slide, the next click will eject you from the slide show mode back to editing mode. Use the arrow keys to navigate among slides. If you like, you can also save the presentation as a movie to view in Quicktime on screen. From the File menu, pick "Save as Movie." The options command will give you a chance to add a soundtrack to the slide show as well. When you open the Quicktime file, the movie plays directly, without having to open PowerPoint and start the slide show.

Source:

Microsoft: PowerPoint Solution Center