need help with instructions on how to install a heater core restrictor valve on an 02 Ford focus 2.0 SOHC?

Answer 1

Buy a Chilton or Haynes manual from the auto store...

I believe on that car it is under the dash, in which case, you have to remove the whole dashboard to get to it, it is not hard, but it takes a long time... about 5 hours roughly.

also, when you do it, be sure to drain the coolant out of the radiator via the petcock.