Step two:
Before you begin to do anything, you are going to need to turn off the water at the shutoff valve. After shutting off the water, you want to flush the toilet so the tank and bowl become empty. If there is any water left in the tank or bowl, you can use a sponge to sponge out the water.

Step three:
Now you will need to uninstall the old toilet. To do this, disconnect the water-supply tube from the shutoff valve and drain the water from the tube into a bucket. Unscrew the coupling nut on the supply tube at the bottom of the tank. Remove the hold-down bolts that fasten the bottom of the toilet to the floor. If they are corroded to the point that you cannot remove them, you can soak them with penetrating oil or cut them off with a hacksaw.

Step four:
To remove the old tank you will need to unbolt it from the bowl. Do this by using a screwdriver to hold the mounting bolt from inside the tank, while unfastening the nut with a wrench from below. Pry the caps off the hold-down bolts and remove the nuts so that you can remove the bowl. To break the seal you will need to gently rock the bowl from side to side. Once the seal has broken, you can lift the bowl up to remove it.

Step five:
Push a rag into the drainpipe to prevent any sewer gas from escaping into your home. Using a putty knife, you will need to scrape away the wax gasket that remains on the floor flange. If the bolts and floor flange are damaged you will need to replace them too.

Step six:
Turn the new bowl upside down onto a cushioned surface. Place the new wax gasket over the horn on the bottom of the bowl so that is facing the tapered side away from the bowl. If the wax gasket has, a plastic collar you need to install it so that they collar is away from the bowl. Apply a thin bead of caulk around the toilet base.

Step seven:
Remove the rag from the drainpipe and gently lower the bowl into place atop the flange, you can use the bolts as a guide. Press down on the toilet firmly while gently twisting and rocking it. Use a level to check that the bowl is straight. If needed use plastic shims to make minor adjustments.

Step eight:
Tighten the washers and nuts by hand onto the bolts. Then alternately tighten them with a wrench until the toilet is seated firmly on the floor. Be careful not to over tighten the bolts because it can crack the bowl. Fill the caps with plumber's putty and place them over the bolt ends.

Step nine:
If needed you will need to assemble the flush valve inside the tank and tighten the large spud nut at the center. Place the rubber tank cushion on the bowl. Position the tank over the bowl and tighten the nuts and washers onto the mounting bolts. Hook up the supply tubes and open the shutoff valve.