Park brake problem

Ok, I was trying to take out the radio in my new car since it doesn't work and I couldn't get it to pop out. The radio in my old car just popped out when I pulled it, then you took the wires off. Anyway, the new one is stuck. So I thought maye theres a switch or lever or something to press on the back of the radio but I couldn't get to it without taking out the center console. So I took it out and I had to take off the park brake, but now I can't get it back on. I have no clue how to fix it. Any help?