@C2Q2 the HS210 is for a 3 way switch (two switches controlling 1 light) and you should have another wire called the traveler wire. Its usually red.  Do you have it?  You should have black, white, green and red. 

Ryan

@C2Q2 

If the dumb switch only had 1 black, 1 white, and green(ground), then it is not a 3way switch, you would need the HS200.

And for the HS200 you would need a neutral in the box, if a neutral is there you will find a group of white wires in one wirenut.

Two black wires are required for an HS200

@RyanEverhart789 Many times they run 14/2 from the switch to the light.

The black is the hot and the white goes to the bulb(black lead).

They should put black tape on the white, just lazy sometimes.

I've never seen that.  Learn something new every day. With the HS200 you have 2 blacks, 1 white and a green. How do you wire it up in the scenario you mentioned above?

Ryan

@C2Q2 are there two switches that control the one light?

@RyanEverhart789 

If there was a neutral in the box, and wiring a HS200

Black wire to one of the HS200 black lead, White wire to the other HS200 black lead.

White lead of HS200 to neutral(white) in the box, green to green.