How to make a 3D button in Unity3d

How to make a 3D button in Unity3d? I know "Handles.Button",but I don't konw how to user it.

http://answers.unity3d.com/questions/5676/selecting-through-raycast

If you search the forums for RaycastHit you can find a ton of other topics on this as well.

For instance: http://answers.unity3d.com/questions/9411/open-and-closing-a-treasure-chest-with-a-keypress

And an outside tutorials:

http://www.bleepng.com/blog/2009/05/moving-an-object-with-touch/