If you have an outline that you created inside of another program, such as Microsoft Word, you can open that file so that PowerPoint will convert it to a presentation. When you open a file, simply change the File Type to "All Outlines at the bottom of the screen.

The outline created should use tabs to designate one level from the next. If you are using Microsoft Word, you can also assign the Heading styles to each level in your outline.
If you have already started your presentation, you can use the Insert: Slides from Outline option to accomplish the same task. Here is a sample outline.

When we choose the Insert: Slides from Outline menu, we then choose the file from the list as if we were opening it. Here is the result in Slide Sorter View.
