Here's my DIY on that. You'll need about $80 worth of parts plus the tonneau cover. You won't have to buy the panels because there are lines on the back of the existing panels that will show you the cutouts fo both the side panels and fo the hooks that go on the deck lid. If you have any questions, feel free to PM me. You might get lucky and find the cover that someone is selling. I bought one for $80.
DIY: Steps to add rear tonneau mounts for those without