How to rotate a CFrame object on a pivot point?

I've come up with a script, but unfortunately, it rotates the entire door, I want it to rotate on a pivot point, so it emulates a door actually opening. I don't know which steps to take from here, any help?

local door = script.Parent
local main = door.Main
local button = script.Parent.MainDoor

local open = false
button.ClickDetector.MouseClick:Connect(function()
	if not open then
		for i = 0, 10, .3 do
		print(i)
		door:SetPrimaryPartCFrame(door:GetPrimaryPartCFrame() 
		* CFrame.Angles(0, math.rad(math.pi*0.9), 0))
		wait()
		end
	end