A presentation, like Rome, is not built in a day, so you will probably fine-tune a presentation over time. To open a saved presentation file that you want to work on, follow these steps:
Select File , Open , or click the Open button on the Standard toolbar. The Open dialog box appears (see Figure 2.8).
Figure 2.8. Select the presentation you want to open.
If the file isn't in the currently displayed folder, select the Look In drop-down arrow to choose from a list of other drives and/or folders.
Browse to the location containing the file and double-click it to open it in PowerPoint.