Adding a new Page is identical to adding a section. At the bottom of the Overview section, click on the "Add Page" button to add as many pages as you'd like.
It's most effective if the titles of the pages are straight forward and that each page is broken down to contain only one action. If for example the step is "Setup A Google Adwords Account" and you want to cover how to setup an account step-by-step, that would fit within that same task and you can use subtitles and text formatting to indicate each step.
The step description should also be direct, actionable, and short - without sacrificing understanding and readability. This isn't a book, but an actionable blueprint of the most important steps of the process that will produce the desired results.
To edit or delete a page, just click on the title from the overview to bring up more options: