How do I make a smoothly changing text label?

First of all, the script I wrote doesn't even work, does anyone have a fix for this?

wait(1)
local textcolor = script.Parent.TextColor3
while true do
    textcolor = Color3.new(1, 0, 0)
    wait(1)
    textcolor = Color3.new(1, 0.470588, 0.0941176)
    wait(1)
    textcolor = Color3.new(1, 1, 0)
    wait(1)
    textcolor = Color3.new(0, 0.666667, 0)
    wait(1)
    textcolor = Color3.new(0, 0.666667, 1)
    wait(1)
    textcolor = Color3.new(0.333333, 0, 1)
    wait(1)
    textcolor = Color3.new(0, 0, 1)
    wait(1)
end

Next, how do I make it do this smoothly? I don't know how to use "Tweenservice." Please help!