It looks like you are already in a Document block, so step 5 is unnessessary. If you place the cursor in the content, and from the View menu, select Collapse Document Block, does that work?
What's going on? Your screenshot looks exactly like the image in the help page, but it turns out that the help page image isn't right. As the section title states, this procedure describes how to apply document blocks in Worksheet Mode. Unfortunately, the screenshot shows Maple in Document Mode. You can tell that this by looking at the Markers visible at the left side of the image. The same example is provided in the User Manual, with corrected screenshots. See Chapter 1, Example 9. I'll make sure the help page gets updated in the same way.