To Set Permissions on a Document, Using the Document Properties Dialog

Select a document.
Select Document > Properties.
On the Document Properties dialog, select the Security tab.
When the Security tab page opens, it displays the default inherited security settings. Documents can inherit security items from the Global Datasource, an Environment, a Parent folder and its own folder. You can modify the security settings to specific settings for this document, otherwise the document inherits the default settings.

Users with Global Access Control display in the Users window (left untitled).
Do one of the following:

To set object security on a document, set Security Type to Document.

or
To set workflow security on a document, set Security Type to Workflow.
Click Add to add a user to the Name list.
Select the user in the Name list, then turn on/off permissions for that user in the Permissions list.
Do one of the following:

Click OK.

or
Click Add to configure more users' permissions for the folder.