Set a bucket under the water to catch any drips. Plug the sinks with the drain stoppers.
Turn off the water to the sink from the valve under the sink or the main water supply to the house. The main water supply valve is usually found near your water meter.
Work plumber's putty in your hand, then spread it into a ring. Press the putty down around the faucet holes. If the faucet has rubber rings at the base, you don't need plumber's putty.
Insert the faucet straight down into the holes so it is aligned and flush with the surface. Press it into the putty.
Slide the washers onto the stem below the sink and roll a tightening bolt up. Check the faucet to ensure it is level and even. Tighten the bolt with the basin wrench until the bolt is snug. Do not force it past this point or you can strip the threads.
Insert the taps into the holes and press into the putty so they are straight and aligned. Roll the washers and bolts up from the bottom and tighten them with a basin wrench.
Install the water lines using flexible water supply pipes. Use supply pipes just long enough to reach the water supply and faucet. This creates a direct line from the water to the faucet.
Turn the water back on and test the taps.