How do I make magic, like lightning, or fire?

If you wanted to make a ray out of a staff, you could use raycasting http://wiki.roblox.com/index.php/Raycasting or, the lightning would depend on all of the angles (if its detailed). If you wanted to make it a straight line with a random position, you could do this

function lightning()
b = Instance.new("Part", Workspace)
b.Size = Vector3.new(2,100,2)
b.Anchored = true
b.TopSurface = 0
b.BottomSurface = 0
b.BrickColor = BrickColor.new("Bright yellow")
b.Transparency = 0.4
b.CFrame = CFrame.new(math.random(60), 0, math.random(60)) 
end

while wait(5) do
lightning()
end

i only know how to make fire.

To make fire - right click on your model/brick (ON ROBLOX STUDIO) and go on Insert basic object, then look for the fire, add it and done!

Maybe someone will help you with the lightning

A fire is simple, its not even required to be a script. Simply go into your Basic Objects tab and insert a fire to a part. You can then go on your properties tab and then edit the fire settings.

x = Instance.new("Fire") x.Parent = script.Parent