When you want to work with an article in the view My assignment you start by choosing the date when your assignment is planned.
When there is an article created on the assignment you click on the article. You see that your article will get a black border so you easily see which assignment you are working on (1). The article will be opened to the right of the screen (2). You work on your article and click on Save when you are done with your editing (3). You can also click on Close if you have nothing to save (4).