Clearly, had I been thinking, I would have used something that would show some contrast, but the back of the work is beige, the mat is beige, the tape is beige. I think you can still see the T, though.
3. Flip your artwork back down. See how that hinge works! Now do the same thing to hinge the top of the mat to the top of the backboard.
4. Let the tape dry, close it up, sign your name in the front right corner, and you're done!
Ok, so I hadn't signed this one before I took the picture, but you know what to do. That's all there is to it.