Measure the paper wall hanging carefully to determine where you want the the top edge of it to hang on the wall.
Use a light pencil and level to transfer a perimeter about ½-inch smaller than the art to the wall. If the art is more rectangular than square, adjust for this as you draw the pattern on the wall.
Draw even spaced cross hatch marks every 6 to 8 inches along the perimeter. Before you drill into plaster walls apply small pieces of masking tape at each location first to keep the plaster from crumbling.
Purchase the correct length spacing sleeves and screws depending on whether you want the art to hang flat against the wall or to float away from it.
Place a drill bit of the correct diameter for the screw anchors into your drill and holding the drill perpendicular to the wall, drill holes at the corners and at each cross hatch mark you made. Make sure to make the holes deep enough to receive the screw anchors.
Remove the masking tape if you used it.
Fit screw anchors into each hole, tapping them down in place if necessary.
Screw flat head screws of the correct size all the way down to the surface of the screw anchors or the tops of the spacing sleeves. It is important to use flat head screws because the tops form the mounting surface for the art and provide the surface to attract the super magnet.
Secure the upper left and lower right corners of the art in place with super magnets placed on the surface of the paper and positioned so they engage the screw heads underneath. Secure the other opposing corners next, and then the mid points along the top, bottom, left and right sides. And place magnets on the screw heads around the perimeter, adjusting and stretching the paper as you go.
Cut and drill, or have the plastic or picture framing shop fabricate a piece, of Plexiglas thick enough not to warp and large enough to cover and protect your paper hanging. Be sure and leave enough extra around the edges to allow you to mount it without puncturing the paper behind it.
Transfer the position of the holes in the Plexiglas to the wall and drill and fit screw anchors as you did for the wall hanging.
Position the Plexiglas by putting the screw through a plastic or rubber washer, the Plexiglas, and then the spacing sleeve long enough to clear the surface of the art. Tighten into the screw anchor.