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).
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.