To create a new article from the knowledge management area, first you'll need to drill into a Collection that you'd like to create the article in.
From there you have two options to create a new article:
From the top right, click on the New Article button
To the right of any category, click on the ... button and select New article here
In the modal that appears, enter in a name (which of course you can edit later, and select which category it should belong in.
You'll then be taken directly to the article to start creating your masterpiece.