I do not use Hexagon but on Youtube are many videos that might help
http://www.youtube.com/watch?v=kVu9oy0xnlkhttp://www.youtube.com/watch?v=iz0ZCwvMUtEThere is a surface tab with a smoothing icon.
There are many different kind of smoothing options but in general when you use the slider there ,
bigger numbers mean more smoothing ,
but at the same time bigger objects (more polygons) too when you export them.
So be careful and use not too big numbers if you are not sure what you do.
When you export as OBJ it exports at the smoothing level you used .
Look at the attachment here too please. Hope this helps Elipsis1