How do a replace an old baseboard thermostat with a wifi thermostat

I don't know if this is a dual pole or single pole thermostat (n00b here, don't know what I'm talking about). I don't even know what voltage this is (240 or 120).

But here's a photo of the wiring:

I bought a wifi Honeywell which includes a number of different wire connections in the back (says, "will not operate without the wire C connected"):

1) Will this work, or do I need a different thermostat for a baseboard heater?

2) I see three wires connected to the old, knob-driven thermostat: red, black, and white. BTW, the old thermostat says Load is black and Line is red. Which wires do I connect to which terminals on the new wifi thermostat?

FYI, I did turn off the power at the breaker. That switch connects to 3 thermostats+baseboard heaters in total. The thermostat I'm working on is only connected to one heater.