I have a 2000 Civic Si

I noticed my rear brake pads we getting low and so I decided to change them myself. I took off the wheels, disconnected the caliper and took out the pads. Here's where I started questioning myself. My friends said you have to use a C clamp to compress the piston and it wouldn't budge. Finally I called one of my friends who used to have and Integra and a CRX. He said you use a big screwdriver to twist the piston in like a screw. So I did that. After that I put the pads in and reassembled. I got the car out on the road and started testing the brakes. It seems that they are working at all. When I pull the E-brake it is not very firm, the wheels won't lock up like they used to. It rained the other day and I was driving on pavement and I hit the brakes pretty hard and the fronts locks up and I could tell the rear wasn't even engaged. What should I do about this? I'm thinking there is something I missed that would reset them.