The cables are in sequence. The wires are in parallel.
The cable will have ground and two hot wires, we'll call them black and red. The "red" wire may be the white wire taped red, or even taped black. Doesn't matter which.
Red and black come from the panel, stop at heater 1, and continue to heater 2.
At heater 2, they terminate with red and black on opposite poles of the heater.
At heater 1, red and black are each tapped. These red and black taps go on opposite poles of the heater.
Don't forget a branch for your thermostat. That must come off the first heater in the chain. It should be 12/3 cable so you have a chance of upgrading to a smart thermostat later. (the third wire isn't neutral, it's always-power for the 'stat). I'm not sure of that's required by Code for 240V heaters, or for Canada, but do it anyway - you'll thank me later :)
You don't want thermostats at the heater, because you want the heat switched based on the room's temperature, not the heater's. Right at the heater is obviously much warmer than the rest of the room. Even a remote thermostat can be thrown off by the heating that occurs inside its wire connections. The cure there is go with a 24V/relay/low voltage system, as a bonus that lets you use modern 'stats like the Nest.