1996 Grand AM GT Brakeing problems

When I slow down in my 96 grand am gt 4 door sadan, pressing the brake half way down does nothing. It takes 75% or more pressure on the brakes to make it even begin to stop, plus i have to press them really hard to stop fast (almost to the floor). Also, when its in the prossess of comming to a stop at lower speeds, the car begins to *rock* forward and backward (only when I am holding the break down). What I mean is it will just go forward alittle hault real fast go forward alittle more hault fast ect ect.. then stops completely if I ram my foot into the break pedal.

ANy ideas on whats wrong? Just a guess but maybe I need new break pads? (I don't know anything about cars, this is my first car)
thx
-dan

You may not need new pads, you may just have to bleed the brakes.

what does *bleed the brakes* mean? how do I do it?

Bleeding the brakes means you take all the air out of the brake lines. If you just bought this car then someone may have changed the pads and not bled the brakes or not bled them properly. As far as bleeing them goes, i would suggest you find someone who knows how to do it and have them help you. I will tell you basically what you do though. If you search online you can find more detailed information. Basically you need to get to your brakes, i find it easiest to take the wheel off. You need to look for the caliper, which is a metal piece that clamps over the rotor (the round disk), sorry if you know this already but im assuming you dont. On the caliper there will be a little thing that looks like a bolt sticking out of it. I havent messed with the brakes on my 96, so idk exactly where it is located. Anyways this piece is where you bleed the brakes, you will be able to tell if its it by looking and seeing if theres a hole in the top. What you need to do next is losen this a tiny bit. Then have somone pump your brakes, if there is air in your line then it will come out. Once all the air is out, you will see brake fluid come out of the hole. When this happens, tighten the bleed screw. Do the same thing on the other side. But once again i suggest you find someone who knows how to do it help you. If you want to try it yourself then do a search on the internet and find a more detailed description. But thats basically it. While you have your tire off you can look and see how worn your pads are, just to see if they need to be replaced. Hope that helps some.

http://www.carcentral.net/content/guides/HowToBleedABrakeSystem.php

That site gives a good description, the method i told you is the manual method.