Turn off the water at the toilet stop by turning the handle clockwise. Drain the tank by pulling on the handle. Take a sponge and bucket to soak up the remainder of water left in the tank. If needed, use some paper towels to finish the job.
Now that the tank is empty, it's time to address the bowl. Since there's still water left in the trap, take an ordinary plunger and press it once or twice as you would with a clogged toilet. This will force all the water out of the trap making the old toilet ready for removal.
The first step in actually disconnecting the toilet from the bathroom is to unscrew the supply line from the stop using a crescent wrench.
Next, disconnect the tank to bowl nuts on the tank. Simply use a long screwdriver to hold them in the tank and then loosen them from the underside. Now the tank is free from the bowl and can be easily lifted.
Line up the closet bolts with the bowl and gently let down the bowl.
To make sure a proper seal is created with the flange and drain, temporarily add the seat and sit on the toilet. The added weight will evenly press the seal tight.
Tighten the provided nuts over the closet bolts and tighten.
New stainless steel supply lines from the ballcock to the stop should be installed.
Next, open up the valve to let the tank fill about 1/4 of the way full. Now, check for leaks.
Add the toilet seat and bolts; adjust the float slider if necessary.