Can anyone add a round bevel to a 3D model?

[Elaphe]

I need a little favor. I have a .stl I have made with a very simple program. It doesn't allow rounding custom shapes, only the default shapes that come with the program. I would like to add a round bevel to the top face of my model. Can anyone explain how to do this with Fusion or just do it for me? Thank you.

The file: http://www.alvarezeninternet.com/temp/botonera.stl
[mod edit: fixed that for you - the English word you wanted was "bevel", not "bezel"]

 

[Elaphe]

I have been able to do it easily with a program called 123D Design.