How exactly do you hang this tv stand?

I've been dying to get a wall mount for our 36" tv. But I haven't wanted to spend over a hundred dollars on one. So now I've found this one, for so CHEAP! But now I'm left with figuring out how to hang it. I have a fireplace and I would like it to go above the mantel. In fact, that's really the ONLY place to put it. Right now, our TV is on a stand in front of the fireplace, blocking it. But I'm sort of afraid of trying to find studs, or what exactly IS behind the sheetrock on the wall there. I have seen people in our complex with their tv in this exact spot (wall mounted, exact same apt) so I know it's possible. I just have no idea how to do it. Husband isn't exactly good with this kinda stuff either. Also, are all of the stands universal? How do I know it will fit the back of my tv? I've got a 36" LG LCD