Questions on Adobe Camera Raw

During the last few days, the class has been learning about how to use Bridge and Camera Raw. I understand a lot of the basic things, like the zoom tool and cropping, etc., but I think I still need a little polishing up on my understanding of histograms. I get that they move as the image's exposures change, but and I understand that peaks on either end of the histogram mean that the image is either overexposed or underexposed. I think I still need help on understanding what all the peaks in the middle mean, and what all the different colors there mean, too. I think I have a general idea of it all, and could make guesses, but I could definitely do with more practice on my own images. I'm just hoping that I will understand this all with practice.