Well, it sounds like you just need more practice, to be honest. There's no magic fix for this stuff. You just have to spend time in training learning the timing. My roommate, who doesn't play fighting games, was just in challenge mode learning this stuff to. He was trying to figure out why stuff wasn't comboing together and why the character kept teching out. I'm trying to explain to him that he's timing his button presses wrong. He's trying to mash things out, when it should be more fluid. Also, having trouble connecting normals into specials so they combo. He was doing it too slow so it would never connect. A lot of times spacing plays a factor into whether or not your combo will work, too, so pay attention to that.
QCB=quarter circle back. 63214+C, so if you think of all the points on a d-pad or stick, there's 9 points. Number notation is just an easier way to show a motion on the joystick. 5 is neutral. So 236 is actually just quarter circle forward, or QCF.
Active frames is how many frames your normal, special or whatever is out for. Don't worry about that stuff if you don't plan on getting heavily into the game. Even then, it's still not that important. I don't pay attention to all the technical stuff most of the time.