my land rover 2000 discovery series 2 just started overheating. what part should i get fixed or changed on my car and show me a diagram to change myself if possible. please help. thank you.

 

we're going to need more information than this. Are you leaking coolant from anywhere? Any strange noises from your water pump? Have you replaced the thermostat recently?

 

Based on your post, you have no mechanical experience and it would be wise to let a Rover mechanic, not the dealer, look at the system and find/repair the problem. In the mean time don't drive the truck till you fill the coolant bottle all the way to the lid, start the engine, let it idle till warm, 5 minutes, shut it off letting it go stone cold and refill the bottle. Then call around, find a shop and get it to them.
I am serious, don't drive it for any reason other then to go to the shop or your could toast your engine.