How do you use the type of "Fireball" Scripts, with tools?

I've been working on a game for a while, and I'm wondering how they make a script, where if you press something, it will make you do tricks, while you're holding a tool. As in the keydown event, but I don't know how it does what it's doing. How does it shoot out the fireball, AND cause damage, at the same time? How does the fireball even appear!?? I'd think it'd be

Instance.new("Randompart",workspace) 

But the problem with that is, the brick won't spawn near the character's hands. It'd spawn somewhere random. How do you do that as well?? I'd think this would be in the functions, as tags because keydown events, trigger functions.

First you need to put that parts name Ex. Local p = Instance.new("",workspace). second its part not Randompart then you define the part its size ,shape , color ,etc.

local p = Instance.new("part",workspace)
p.Color = "Any color you want"
p.Size  = the size
p.Cancollide = true/false
p.transparency = its transparency
and some others. 

To find the player's hand you need to locate it

local right_arm = vCharacter:FindFirstChild("Right Arm")
if (right_arm ~= nil) then
local joint = right_arm:FindFirstChild("RightGrip")

Im not a scripting expert but i think this would work.