Hey impulsive. First, don't adjust the cable, readjust it back to the point it was at before. Secondly, here's what you need to do:
1. Remove rear wheels.
2. You'll now see 2 rubber grommets on the outside of the rotor, remove 1 of these.
3. Make sure your handbrake is down
4. Rotate the rotors until the hole without the grommet is at the bottom, now look through this hole with a light and rotate the rotors left or right a bit until you see a cog.
5. Put a flat blade screw driver in the hole and rotate the cog up or down intil the rotor locks up.
6. Now rotate the cog the opposite way 2-4 CLICKS, the rotor should move freely again.
7. Repeat steps 4-6 for the other rotor, moving the cog in the opposite way to the other wheel (ie if on the right wheel you pushed the cog up, then on the left you push it down to tighten the hub).
Now that you've done this, test the hand brake, does it feel good? If it is, then put the wheels back on, drop the car and test the handbrake out.