To fix the pan, mark the screw positions on the floor by tapping a nail through the screw-holes, and draw round the base on the floor so that you can replace it in exactly the same position. Drill holes in the floor at the points marked and finally fit the screws. If it's a solid floor, of course, it's essential to use plastic or fibre plugs in the screw holes.
For fixing the pan, it's advisable to use brass non-corroding screws with a lead washer slipped over each one so you won't crack the pan as you tighten the screws. Screw the pan down, checking that it is exactly horizontal with the aid of a spirit level laid across the top of the bowl.
If it is not dead- level, pack the lower side with thin wood or plastic strips. The latter are more suitable because thin wood rots too easily. Finally check that the outlet of the pan is firmly pushed into the connector and that you've followed any specific fitting instructions from the manufacturer.
Fitting the cistern
Fix the new cistern to the wall at the level above the pan recommended by the manufacturer. In the case of a separate cistern, secure the upper end of the flush pipe to the cistern, usually by means of a large nut, and the lower end to the pan's flushing horn with a rubber cone connector.
With a close- coupled suite, follow the manufacturer's instructions. You will now quite likely have to extend or cut back the water supply pipe to connect it to the new cistern. Complete the job by cutting and fitting a new overflow.