Replacing two-switch, combo paddle light switch?
You need to identify the wires in the switch box.  They are possibly like so:
      (Click for larger view)
      
(The Hot wire is usually either in the center or isolated on one side, in such combo switches.)
But you need a voltage tester or ohmmeter to be sure.
If you get it wrong, swap the wires around as indicated in the testing section, below.

Once you have identified the wires, hook them up like so:
      

Make sure the breaker(s) is/are switched off.
Use a voltage tester to ensure there are no live wires in the switch box.
Screw the COM B screw in all the way, it will not be used.
Leave the jumper alone (it is not a fuse).
Connect the Bare (ground) wire to the ground/green terminal at the bottom.
Connect the Light wire to the SP A terminal.
Connect the Hot wire to the COM A terminal.
Connect the Heat wire to the SP B terminal.
Screw the switch into to the switch box, keeping it plumb.
Install the cover plate.


Test the switch:

Turn the power back on.
The top switch should control the light (for safety and by convention) and the bottom should control the heat.
If both come on but the bottom switch controls the light, turn the power off and swap the wires on SP Aand SP B.
If only one of the 2 circuits comes on, you have the hot and that circuit's wire misidentified. Turn the power off and swap the corresponding SP wire and the COM A wire.