If you do not have experience or are not confident to carry out this task you should call a professional plumbing tradesmen like Bromley Plumbers who have all the tool for this job.To begin a Bidet fit you should plumb the drain lines to the manufacturers specifications. Spread plumbers type putty on the base of the bidet tap, and then place the tap body into its mounting holes. Screw on the washers and locknut for the tap body shank and tighten it by hand. Put a roll of plumbers putty underneath the drain flange. Place the flange in the drain hole, and then fit the gasket and washer, threading the nut on the flange. No need to tighten. Fit the pop-up drain appliance by using the manufacturers diagram. Put the bidet in its final location. Make sure it is in line. Mark the location of the two side-mounting holes onto the floor through the pre-drilled holes on the stool. Remove the bidet and drill the correct size pilot holes through the marks on the floor. Push the floor bolts (supplied with the bidet basin) into the holes. Place the bidet so the floor bolts and their holes line up and mate. Make the water connection to the bidet tap with compression unions and dont forget to fit the hot/cold supplies to the correct ports on the bidet. Connect up the drain line by attaching the P-trap to the tailpiece for the drain. The trap then attaches to a branch drain line coming from the wall or floor in the same way as a sink drain. You may need a professional like a Bromley Plumber to ensure the job is done to the current regulations.Take the aerator out so any foreign bodies in the supply line will clear and then switch the supply on. Look for any leaking. Make up the bolt caps and thread them onto the floor bolts.