Underneath the main content area of your page, in the lower left hand corner you will see "Right Column."
Click "Right Column" to expand the editor for this section.
This section acts exactly the same as your main content area, with all the same features. The difference is that this content will be displayed in a small column on the right side of your main content area. For an example of this in action, take a look at our About Us page.
Once you've entered the desired content into your Right Column, click "Submit."