When you open the site (and assuming you’ve already signed up) you’ll find yourself looking at a library of all of the documents you have. Creating a new document just takes a press of a button, and then you have a blank template in front of you. While it’s not expressed outright, there are shortcuts you can use to create various headers, bold and italicize font, etc. It’s a little confusing at first, but luckily Editorially proved a little cheat sheet you can find in the dropdown menu.
At first it’s a little confusing, especially because even though you type the shortcuts, nothing happens or shows up until after you save the draft mode, and go into publish mode to see the style changes. Aside from the formatting to the left, there’s nothing else you can to do change the style.