There are two ways to open a Microsoft PowerPoint presentation from the Backstage view:
From the File menu, select Open. (In Microsoft PowerPoint 2007, select the Microsoft Office button and click Open.) Select the location of the file, and in the Open dialog box, navigate to the file you want to open and double-click it or select it and click Open.
For files you have used recently, select Open from the FILE menu and then select Recent Presentations. Then, select the file. (This option is not available in PowerPoint 2007.)