From the Actions menu, select Create Revision:

The following window will appear:

RevisionShows the revision number about to be created (not editable).
Revision DateShows the revision date for the revision about to be created (not editable).
Created ByShows the creator of the revision about to be created (not editable).
Revision NoteEnter any notes, comments, or reason for the release. These notes can be modified after the revision is created.

Click the Save button to create the revision. Click the Cancel button to cancel the creation of the revision.