Shut off the water supply valve behind the toilet.
Remove the toilet seat and the two bolts that hold it in place. Set the bidet attachment on top of the toilet so that the two holes in the bidet line up with the bolt holes in the toilet.
Insert the bolts from the bidet's hardware package into the holes in the toilet. Place the toilet seat on top of the bidet. The bidet's bolts will have holes in the top so you can insert the toilet seat's anchor bolts. Insert and tighten the bolts to secure the toilet seat.
Disconnect the water supply line from the toilet. Attach a t-shaped connector to the end of the line. Connect one end of the bidet's water supply line to the t-connector and the other end to the bidet's cold water inlet. Connect another water supply hose to the t-connector and the toilet.
Attach another t-connector to the hot water line behind the bathroom sink, if you are installing a bidet that has a warm water option. Attach the bidet's hot water supply line to the t-connector and the bidet. Attach another supply line to the bathroom sink and the t-connector.
Open the water supply valve for the toilet. Test the bidet to make sure it is working correctly and there are no leaks at any of the plumbing connections.