also check out  How Drafts Work

You never know when you're going to get a phone call and be distracted until your sign-in times out, or when your battery on your notebook dies. Draft saving prevents you from losing all your work. 

put your title in the appropriate field

put your body text in the text body field.

click on the Save Draft button. That's it. 

go to submit article

throw some letters into the title and text body so you can click on submit. That brings up the second page of the article submit system.

click on restore draft.

You will see something like this, with a list of all article saved drafts. 

look to the most recent one and check it off. 

Click on Restore Draft button

Now you can work on the article and publish it. 

Do NOT retrieve drafts after the article is published.