With a project on the timeline, click the 3-lined menu, top left, then FILE | SAVE PORTABLE PROJECT AS... 
This will back up all source files and the VPJ control file to the target folder you choose on the hard drive.
Later, click the VPJ and the project will re-load.
For protection, Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the caret to the right of the Save Project button on the toolbar.