In the 'Content' tab (1), click 'Reading Materials' (2) in the left hand menu bar. Then click the 'Create' (3) button.
Title the article (4), and decide if you want it public (5) or just accessible to clients with the URL. Tag the article (6), and begin adding content (7). Upload a picture (8), and when finished, click 'Save' (9).
Once saved, you will find the new article in you Reading Materials. Click 'View' (10) to view the article as seen by a client. To delete the article, click the garbage can icon (11).