How to figure out wire types while replacing old switches with new ones
You may be out of luck. Mechanical switches don't need a neutral. Electronic gizmos generally do. 


The black wire that is permanently hot connects to BK
The black wire that is switched hot (goes to load e.g. lamp) connects to RD
The white wire that is missing Connor spotted connects to WH
Nothing connects to YL/RD (that is only for 3-way switches).
A pigtail from the ground wire connects to the green terminal screw.


Worst case: You might need to run new wiring to the switches. That might mean opening up the walls.