To start a new presentation, click the Microsoft Office Button 
and click New.
In the New Presentation window, start with a blank slide, or base the presentation on a template or an existing presentation.
New file format PowerPoint 2007 saves new files in a new format. You can open old presentations just fine and save in the new format. But the file format change does affect presentation sharing between PowerPoint 2007 and older versions of PowerPoint. The last lesson goes into this in detail.
