Shut off the water supply to the toilet by firmly closing the supply valve.
Remove the tank lid, and flush the toilet, holding the lever down to let as much water drain from the tank as possible. Use a sponge to soak up the excess water in the tank and a plunger to force as much water as possible out of the bowl.
Pop the caps from the base of the bowl.
Remove the nuts with an open-ended wrench. You may need to hold the bolt still with a pair of needle-nose pliers. If the nut is rusted to the bolt, you may have to break it off.
Disconnect the toilet supply tube from the toilet stop.
Shift the toilet back and forth while lifting it off the flange. If you're working alone, remove the tank by unbolting it from the bowl before you attempt lifting the toilet from the flange.
To prevent sewer gases from entering your bathroom, stuff a rag into the drain opening.
Scrape all the old wax from the flange, and check for cracks. If the flange is cracked, replace it. Be sure to wear gloves when scraping off the old wax.
Place the new toilet bolts in the flange with the bolts pointing up.
Remove the rag from the toilet drain, and place a wax seal on the flange. Squeeze enough wax onto the bolts to hold them upright. Use a deep-seat wax seal when replacing older water toilets.
Set the tank seal in place.
Place the tank on the bowl.
Drop the tank bolts through the appropriate holes.
Tighten the bolts until the tank doesn't wobble. Be sure not to over tighten the bolts: you could crack the porcelain. If you're working alone, attach the bowl to the floor before installing the tank.
Slowly set the tank and bowl assembly onto the wax seal, lining up the bolts with the mounting holes in the bowl.
Tighten the nuts onto the bowl until the assembly doesn't wobble.
Reconnect the toilet supply tube to the tank.
Refill the tank, adjust the water level, and check for leaks.
Attach the seat using the seat bolts provided.