You can create an animation, or you can use a tween, whichever you prefer. Tweens are good for simple things like moving objects from A to B. Animations are perfect for everything that's more complicated than that -- bounce effects, complex movement, multi-object movement, etc.
If going the tween route, you need a tween on the target object -- for example TweenPosition. This tween needs to have the "From" and "To" parameters set. It also needs to start disabled (just disable the script).
You then attach UIButtonTween script to your button, and make it point to the TweenPosition object you added above. Hit Play, click on the button, watch what happens.
