I can't get too specific without knowing the type of car. It requires draining the coolant and removing engine components before unbolting the old pump and installing the new one.
Well every car is different. Some cars require just unbolting the pump from the engine block however other require going into the engine to replace. Both usually require removal of accessories and their related belts. Look online to find out what type of pump you have and how to change it. Also look for a repair or service manual online.
The process will depend on the make, model, year of the vehicle. Basically you drain the coolant, dis-assemble the engine, replace the pump, refill the cooling system, and bleed it.
You will need to find the other one which is usually marked under the hood near the firewall. Remove the bolts from the old one and install the new one.
It depends on the vehicle. Usually a water pump is attached to the engine by a few bolts and gaskets. Follow your coolant hoses back to the engine to find the water pump.
Installation of a water pump varies completely in relation to the vehicle type. In any case you would need to drain your radiator first. Then locate the pump on the engine, in some cases it may not be visible by simply looking under the hood. Remove all that remains to gain access to the pump then replace with new gaskets.
To install a car water pump put that pump in proper position then install the timing belt that matches with the timing of firing order of ur vehicle. be careful about the head gasket
