The File menu is fairly straightforward and gives you options on what you can do with a document. The dropdown contains the following options;
Open Other Document
Clicking these options will proceed with these actions. We have covered how to create new documents from the dashboard previously as well as deleting documents. This is just another way of accomplishing those goals.
The duplicate document option will ask you for a name for the new document and then copy over all the information for that document into a new document. If you are A/B testing or looking to take a document in a specific direction but are not entirely sure then this is a good option to take.
All documents autosave on a regular basis whilst you are in a Document page so they will always be up to date with the latest content you have added to them.
Opening another document will also do just that, you will get an option of all the documents you have in your account and it will open your selection so you can work on that different document. Fairly simple to navigate and fairly simple to use. Click the File text at the top of your Document to make use of any of these options.