How do you make an object spin?

Well it's pretty simple you can use a for loop if you want the part to spin a certain amount of times or a while loop which would make spin infinitely unless you call a break which would stop it there are other methods of spinning of objects but this is the way that i know how.

--parts name will be brick

brick = script.Parent
for i = 1,100 do
brick.CFrame = brick.CFrame *CFrame.Angles(1,0,0)
wait()
end

--or a while loop

while true do
wait()
brick.CFrame = brick.CFrame *CFrame.Angles(1,0,0)
end

Set Anchored to false on the part and then set the RotVelocity property to the desired direction you want the part to rotate.

while true do
script.Parent.CFrame = script.Parent.CFrame * CFrame.fromEulerAnglesXYZ(0,0.1,0)
wait(0.01)
end

OR

while true do
script.Parent.CFrame = script.Parent.CFrame * CFrame.fromEulerAnglesXYZ(0.05,0.05,0.05)
wait()
end