Open module My Company
On the left you will find various modules. Here you will see the module "My company". By clicking on it you will get several options under this button.
In the overview that is located under "My Company", you will find the button "Documents". Clicking on this will open the screen with an overview of all your documents.
To the left of the name, in the column "Status" you will find a white button "Public". If you click on this button you will get a screen where you can enter a password. If you have entered a password press add and the document will be protected.