Can't get local script to communicate to the server?

Right then, I've got this drive system for a train that i've been working on. It all works fine and dandy. However, it ajust's things like the chuffing sounds for it through the local script, and as a consequence only the driver can hear it. In future i'll be adding things like particle effects as well. What i'm aiming to do is to make it so everyone can hear it and I've read up about remote events and functions but after about a week of confusing myself I've reached the point where i could do with a bit of guidance.

Anyways, here's the code:

wait(.5)
vehicle = game.Workspace:FindFirstChild(script.Parent.Train.Value)
mouse = game.Players.LocalPlayer:GetMouse()
Chassis = vehicle.Chassis
reghinge=Chassis.Regulator.HingeConstraint
regvalue=Chassis.Regulator.Value
revhinge=Chassis.Reverser.HingeConstraint
revvalue=Chassis.Reverser.Value
cutoffhinge=Chassis.Cutoff.HingeConstraint
cutoffvalue=Chassis.Cutoff.Value
airbrakehinge=Chassis.AirBrake.HingeConstraint
airbrakevalue=Chassis.AirBrake.Value
brakeseat=vehicle.Body.BrakeSeat
powerseat=vehicle.Body.PowerSeat
driveseat = vehicle.Body.Seat
chuff=vehicle.Body.Chimney.Chuff

function KeyPress(key)
	if key == "e" then
		if regvalue.Value < 20 then
			reghinge.TargetAngle=reghinge.TargetAngle-5
			powerseat.Torque=powerseat.Torque+.07
			regvalue.Value=regvalue.Value+1
			chuff.Volume=chuff.Volume+0.03
		
			
		end
	end
	
	if key == "q" then
		if regvalue.Value > 0 then
			reghinge.TargetAngle=reghinge.TargetAngle+5
			powerseat.Torque=powerseat.Torque-.07
			regvalue.Value=regvalue.Value-1
			chuff.Volume=chuff.Volume-0.03
		
		end
	end
	
	if key == "w" then
		if revvalue.Value < 1 then
			revhinge.TargetAngle=revhinge.TargetAngle+15
			powerseat.Throttle=powerseat.Throttle+1
			revvalue.Value=revvalue.Value+1
		end
	end
	
	if key == "s" then
		if revvalue.Value > -1 then
			revhinge.TargetAngle=revhinge.TargetAngle-15
			powerseat.Throttle=powerseat.Throttle-1
			revvalue.Value=revvalue.Value-1
		end
	end
	
	if key == "r" then
		if cutoffvalue.Value < 4 then
			cutoffhinge.TargetAngle=cutoffhinge.TargetAngle+87
			powerseat.MaxSpeed=powerseat.MaxSpeed+9
			cutoffvalue.Value=cutoffvalue.Value+1
		end
	end
	
	if key == "f" then
		if cutoffvalue.Value > 0 then
			cutoffhinge.TargetAngle=cutoffhinge.TargetAngle-87
			powerseat.MaxSpeed=powerseat.MaxSpeed-9
			cutoffvalue.Value=cutoffvalue.Value-1
		end
	end
	
	if key == "]" then
		if airbrakevalue.Value < 6 then
			airbrakehinge.TargetAngle=airbrakehinge.TargetAngle+30
			brakeseat.Torque=brakeseat.Torque+.3
			airbrakevalue.Value=airbrakevalue.Value+1
		end
	end
	
	if key == "[" then
		if airbrakevalue.Value > 0 then
			airbrakehinge.TargetAngle=airbrakehinge.TargetAngle-30
			brakeseat.Torque=brakeseat.Torque-.3
			airbrakevalue.Value=airbrakevalue.Value-1
		end
	end

end


function LeaveSeat(child)
	if child.Name == "SeatWeld" then
		script.Parent:Destroy()
		
	end
end

mouse.KeyDown:connect(KeyPress)
script.Parent.Parent.Parent.ChildRemoved:connect(LeaveSeat)

Any help is very much appreciated!

I would use remote events (i only recently learned how to do this but it's quite useful), Insert a new remote event into ReplicatedStorage (so both Server and Local scripts can access it) Name the RemoteEvent what ever you want and go into your local script.

Under

if key == "WhichEverKeyYouWant" 

put

game:GetService("ReplicatedStorage").EventNameHere:FireServer()

(you may need a new event for every key pressed if you want them to do different things) and then in your regualr script (Server Script) put

game:GetService("ReplicatedStorage").EventNameHere.OnServerEvent:Connect(function()
---Code here (sound effects or whatever)
end)

you can repeat this process with multiple events as long as they all have seperate names sorry if this is more like a tutorial than "help" but i hope it works if i'm not giving you a good enough example i'd reccomend searching "Remote Events" on the Roblox API Reference