To open an existing document, follow these steps:

1. Go to the Backstage view and click on "Open."
   
   
   
2. Select "This PC" and then click "Browse," or choose "OneDrive" to open files from your OneDrive.
   
   
   
3. The Open dialog box will appear. Find your document, select it, and click "Open."
   
   
   
4. Your selected document will open on the screen.

For more details about saving documents, check the lesson on Saving and Sharing Documents.