This article will walk you through adding a custom document.
Log in to CoAuthor
In the Projects Workspace, select the name of the project to which you want to add a custom document
In the Documents Tab, click on the Create Document button
In the Create Document modal, enter a Name
Select any document Type
Select "Select File" from the Templates picklist
Select the custom document you would like to add from your local file, then click Open
Click Create
Once your document has been created, it will be displayed in the Documents tab of the project where it was created.