If you want to use the integrated Tween engine in your code, you should use AutoTween.
TweenManager is just the GameObject that keeps track of the tweens.
In order to use AutoTween, you can just call it using TweenManager.AutoTween() in your code, and pass the parameters you want (you can search for " TweenManager.AutoTween" in the code to find some examples).
We'll be adding some documentation and tutorials soon on everything regarding MaterialUI, sorry for that!
If you don't want to do things using code, but do things in the Inspector, you should attach an EasyTween component to the GameObject you want to tween!
Feel free to ask for more detail!