The article will show you how to add project specific encryption to a project that has already been created.
You will need to first export the current project data.
To export the current project data follow these instructions: Export Project Data
Next, create a new project with project specific encryption enabled.
You can see how to do this here: Create Project with Encryption
Finally, import the the project you initially exported into the newly created project.
The instructions can be found here: Import Project Data