the easiest might be to create a regular Eto.Forms.Button and use the Image Property on it. This will display the button borders, hover and mouse down effects by default and the flat image.
To get a bit more fancy, and make a button with your own effects, you could create an Eto.Forms.Drawable which inherits Eto.Forms.Control with various mouse events. Note my example script in this thread.
_
c.