It's fairly easy to install a toilet as long as you have a little know-how and the right equipment. Unless it is a new install, the first step is to remove the old toilet. This is easy to do — unless you need to move the plumbing lines to a new location. If that is the case, call a plumber to move supply and drain lines post-removal.
To remove the old toilet, first shut off its main water supply, which is usually located behind the bowl. Then, flush it to remove most of the water from the bowl. Using a sponge or a cup and bucket, remove remaining water from the bowl. Then, disconnect the water line from the base of the tank. To make the lifting easier, it is possible to remove the tank from the bowl by unscrewing the nuts on the underside of the tank and lifting it off. This is not necessary, though.
Next, pry the plastic caps off the base to expose the bolts holding it to the floor. Using an adjustable wrench, unscrew the nuts. If they are rusted or corroded to the floor, try using a nut and bolt loosener spray or, at last resort, a hacksaw.
Once this is done, rock the bowl side to side to gently to loosen the seal of the gasket on the floor, then lift the toilet and set it to the side. It is a good idea to insert a rag into the flange to prevent sewage smells from entering the room. Do a thorough clean-up of the floor area around the flange, particularly scraping any remains of the wax ring and replacing the hold-down bolts with new ones. Scrubbing the footprint of the old toilet, painting the wall behind it, and/or redoing the floor are easier now than at any other time!
You need to get a few parts before you can install the new fixture: a wax ring or gasket for the base, new hold-down bolts, plumber's putty, bathroom caulk or plaster and possibly a new flange, if the old one is worn out or not raised 1/2 inch (1.27 cm) from the finished floor. While you're installing, remember that most toilets are porcelain and can crack easily. Handle with care as you turn the new bowl over, laying it on a padded, thick surface. Install the new wax ring on the horn of the bowl at the bottom with the smooth, flat side facing the toilet. If the wax ring has a sleeve, it should be farthest away from the bowl.
Insert the hold-down bolts into the flange, and, for ease, place two straws over the top to help guide the bowl over the bolts. If using caulk or plaster as a sealant, then be sure to apply this within the footprint of the new toilet. Remove the rag from the flange.
Now, picking up and turning over the bowl carefully, line the bolt holes up with either the straws or the bolts themselves. Once the toilet is set, do not pick it back up, to prevent damage to the new seal. Gently rock it back and forth to set the wax seal and the plaster or putty seal. Hand-tighten the nuts onto the hold-down bolts, being careful not to over-tighten, as the porcelain can crack. Once tight and level, use plumber's putty to put the caps over the bolts.
If the tank is a separate piece, place the bolts in the holes from the inside of the tank and line them up with the holes in the bowl. Tighten down the nuts from the underside of the tank and adjust the flush valve if necessary. Reconnect the water line and turn the water back on to complete the process.