where do the water goes in on a 2005 mercury mountaineer

Coolant (water with antifreeze) is added into the overflow bottle attached to the radiator cap neck. If you are trying to refill the coolant after draining or other major liquid removal, wait until the engine is cool and then remove the radiator cap and pour the coolant directly into the radiator until it reaches the bottom of the neck. Then fill the overflow reservoir to the cold fill line, replace the radiator cap and run the engine up to operating temp. If the coolant in the bottle is below the hot fill line, add coolant to the reservoir - not the radiator until it is at the line. Turn off the engins and check the level in the reservoir again after waiting for the engine to cool.

Can you put water only in coolant

My truck is completely out of water don't have antifreeze yet can I just put water only

I have a mercury mountaineer we thought it had a blown head gasket so I had it replaced I get it an I half to put water in it everytime I go any were or stop any were I'm so tired of this please if someone knows what's going own please tell me an when I turn it off it smoking like it's running hot but it had not ran hot an the gage works !! Pl pls tell me something I've put stuff in it for it to stop a leak in the radiator I don't no what else to do HELP