Dual light switch changing to dual smart switch
If all you have in the switch box is the black , white and ground this is a switch leg and your new smart switch probably needs a neutral (white wire in the box not connected to the switch) 

The wires connected to the switch now are a hot and a switched hot. Many smart switches need a neutral to provide power for the electronics of the switch.  

If you have a neutral in the box tie the new switch white to the neutral it should be white or gray. The next steps depends on the color wires on the new switches. But if you only have the one cable in the box with 2-3 wires it cannot be done with your existing wiring without additional wiring.