How do I make smooth animations with the character using CFrame, or perhaps 'Tweening' them?

I have not been to sucsessful in making the character have smooth animation without the Animation Editor. Here is what I've been trying

LArm.C0 = CFrame.new(0, 0.5, 0) * CFrame.FormEulerAngles(math.rad(90), 0, 0)

Is this the correct way to do it, or shall I use another method?