Locate the water supply pipe coming out of the wall behind the toilet. Place a screwdriver into the hole behind the pipe's cap. Twist the screwdriver to turn off the water supply. Flush the toilet to empty the bowl. If the bowl does not fill back up, the water has successfully been turned off.
Unscrew the water supply hose from the shutoff valve. Pull off the decorative caps from the two bolts in the bottom, back corners of the toilet. Unscrew the two back nuts with a wrench and the pan head screw located at the bottom of the front of the toilet.
Lift the toilet up and out of the stall. The floor flange connection now will be revealed, secured to the floor where the toilet was located. Remove the four screws in the back corners. Use a wrench to unscrew the nuts from the floor flange bolts at the front of the mounting point. Remove the two screws holding the mounting block in place and lift it off the floor.
Remove the rubber gasket from the pre-installed floor flange left on the floor. Insert the new rubber gasket into this opening.
Place the new floor flange connection onto the floor, lining up the holes on either side with the bolts coming up from the floor flange. Place two hex bolts upside down into the hexagon holes in the back corners of the mounting block. Slide the mounting plates over the hex screws.
Secure the two back corners to the floor with the four self-tapping screws. Put a washer onto each floor flange bolt. Twist nuts onto the bolts. Tighten the nuts with a wrench.
Place the mounting block in front of the floor flange connection. Line up the holes on either side of the mounting block with the holes in the floor. Place a washer on each screw and tighten the screws into the mounting block to secure it in place.
Lift the new toilet and position it over the floor flange connection. Lower the toilet, making sure the pipe in the back of the toilet is inserted into the hole at the top of the floor flange connection and the holes in the back two corners fit over the upside down hex screws.
Slide a washer onto each upside down hex screw. Twist a nut onto the hex screws to hold the toilet in place. Screw the pan head screw into place on the front of the toilet. Push the decorative caps over the back bolts and the pan head screw.
Remove the old gasket from the opening of the water supply valve and push a new gasket in place. Screw one end of a new water supply hose onto the valve. Screw the other end of the water supply hose to the connecting hose fastener on the back of the toilet.
Restore the water supply to the toilet. Flush the toilet a few times to make sure there are no leaks.