Why doesn't my Fireball script not work?

Okay, so i've made a fireball script for a dragon. When test it, on output it says did you forget a colon? The first argument of WaitForChild must be an Object. And here's the script:

sp = script.Parent
head = script.Parent.WaitForChild("Head")

function fire()
	f = Instance.new("Part")
	f.Name = "fireball"
	f.Shape = "Ball"
	f.BrickColor = BrickColor.new("Bright blue")
	f.TopSurface = "Smooth"
	f.BottomSurface = "Smooth"
	f.Size = Vector3.new(3,3,3)
	f.CanCollide = false
	f.CFrame = head.CFrame
	f.Velocity = head.CFrame.lookVector*math.random(60,100)
	g = Instance.new("Fire", fireball)
	g.Heat = 5
	g.Color = Color3.new(255,0,0)
	g.SecondaryColor = Color3.new(85,85,85)
	fireball.Parent = game.Workspace
end

while true do
	wait()
	fire()
end

You forgotten to Anchored the fireball and to make it shoot do this Make sure the fireball is to the dragon mouth like CFrame it to the dragon mouth for i = 1,100 do f.CFrame = f.CFrame *CFrame.new(0,0,-5) wait(0.03) end

Why is it looped, That will lag out your game. Also, it would not fly if you fixed your problem, use this instead.

bv = Instance.new("BodyVelocity")
bv.maxForce = Vector3.new(math.huge,math.huge,math.huge)
bv.velocity = part.CFrame.lookVector*speed