Select the document which has enabled versioning, then select from the Right-click menu or on the Action bar.
Click again to open the Version Info window.
The selected document has been added as the Base Version.
Select CheckOut from the Right-click menu or on the Action bar to start working on the version of this document.
You cannot do some actions which affect on content or information of the document (for example, renaming or editing) in the CheckIn status. You must check it out before you can perform these actions on it.
Repeat selecting CheckIn, then CheckOut to add more versions.