How does one create a door using .KeyDown?

As an example, the one used in Darkness 2. When you are at a certain distance from the door, if you press a certain key on your keyboard, it will open(If pressed, again it closes, but I can do that part.) How do I go about making a door like this? All help appreciated, Thank You. ~ Xduel

Use magnitude to see how far a player is from a certain object, like so

if (workspace.Player1.Torso.Position - workspace.Part.Position).magnitude > 20 then
	--then open door
end

that will check if the player is 20 studs away from the part named Part in workspace and then do the following code

ScriptingHelpers is not a request site but here is the basics of the code that will detect when the player presses e and then prints that the player has.

local Player = game.Players.LocalPlayer
local Mouse = Player:GetMouse()
 
Mouse.KeyDown:connect(function(Key)
	if Key == "e" then
		print("User pressed e")
		-- enter code here
	end
end)

If you need more help here's the wiki page on taking keyboard input: http://wiki.roblox.com/index.php?title=Taking_keyboard_input