Installing bathroom exhaust fan (light, fan, and heater) with three seprate switches on wall

Need help on wiring light unit. Have three plug-ins inside unit. One for light , one for fan , and one for heater. Have three cables coming into unit. All three cables are 2 wire with ground wire. Black wire , white wire, and ground in each cable. One cable goes to a junction box and other two cables come from wall switches. Light plug has one blue and one white wire. Fan plug has one black and one white wire. Heater plug has one red and one white wire. How are the three cables wired to the plugs and ground.Furnace quit working after first attempt.