I use a gym, although I dought you could tell by looking at me. The company I work for has it's own gym right on campus so it's very convienent and free to all employees. The first machine you described sounds like a squat rack to me. This should work legs pretty good, but I think it targest your hamstring muscles (back of your legs). The 2nd machine you describe sounds like a leg curl machine which is also designed to target the back of your legs. I believe the muscles you are trying to work are called the quadroceps, or "quads".

A leg extention machine would target the muscles you want. This is a machine you would sit in and hook the front of your ankles behind a bar. Then you would extend (straighten) your legs outwaords, lifting the bar, and the weights.

Lunges are another way to work these muscles without a machine. Basically put one foot out in front of you, and the other one behind you a little bit. Make sure your feet are both pointing forward. Then just squat down like you're going to touch your back knee to the ground, while keeping your back straight. For some extra resistance, grab a couple of free weights and just hold onto them while doing this. You can do this while standing in one spot, or do it as a walking motion.

I have also done a lot of biking and that helps too.

There should be someone at the gym that could help you out too.

FEEL THE BURN!!!!!