manual

My car is a chevy monza 2000 makes a strange noise they tell me that it is the oil pump and I need to change someone could provide me with any manual or procedure that indicates how to change thanks

Greetings!
In these engines it is uncommon for this piece to be damaged, first ask for another opinion or two more, before proceeding to change the oil pump.
I recommend that if you have no knowledge for the correct disassembly and armed of the pieces, you turn to a qualified mechanic, since you could damage the engine.
The Daewoo Auto I hope 2000 has the same engine as the Monza 2000, except for small variations. You can lower the Daewoo manual I hope it appears in these pages to make you easily with respect to the engine.
To change the oil pump of these engines, the front of the engine must be disassembled, since the oil pump is located in the lower front of the engine.
You must disarm: the alternator and air conditioning straps (stir tensioner), crankshaft pulley, the plastic cover of time strap, time strap, pineapple of the crankshaft, carter (oil tank), oil filter.
Once the oil pump has been removed, the new pump and the assembly of the pieces are assembled, you must take into account the correct assembly of the time belt (camshaft belt) and its adjustment. Also the tensioner of the alternator's belt. Special attention when riding the carter, using the recommended torque and silicone
I hope I have helped, any other doubt, consult the reference manual