Photocopy your picture; if you don't have a copy machine, go to a copy center where you can inexpensively make your duplicate. High contrast, clear images will transfer best. Your photocopy can be color or black and white.
Place your tracing paper over your image and trace the outline of your image. Cut around the outline and discard the inner piece, leaving only the cut-out paper that surrounded the outline. Cut out your photocopied image, as well.
Tape the outer part of your tracing paper outline to your whiteboard; place it over the area where you want to transfer your photocopied photo.
Dip your brush into the acrylic medium. Brush a thin layer of medium onto the white board in the open area inside the tracing paper taped to the board. Remove the tracing paper and discard it.
Place your cut-out image face-down exactly over the area where you just applied the medium. Press it firmly against the medium, making sure all areas adhere. Allow the picture to dry overnight.
Blot the entire back of your paper with your damp sponge. Allow the water to soften the paper. After a few minutes, begin peeling your paper off the whiteboard. Gently rub at stubborn areas with a soft cloth.
Allow your work to dry for another 2 to 3 days before adding other elements to your whiteboard.