This is yet another reason not to buy apple.Here's the answer to the first half of this problem.
That should tell you how to view hidden folders in a hard drive.
Then there is going to be a series of folders (probably) with obscure names. If your lucky there might actually be some that are understandable. The music files are somewhere in one of those folders (probably in another folder, in another folder etc.).Hopefully it won't take too much digging.
From memory of when I last did this (a while ago) all of your music, depending on how much you have, will be seperated into numbered folders. (they might have a letter in front of them like f, not too sure. But having a lot of numbered folders will be a give away.)
This is probably specifically to annoy you as if you have several thousand files you will have several hundred folders,each of which you might have to sort through separately. (although theoretically iTunes could grab all of them in one go.
Now this is the absolute worst bit imo. Unless apple have changed their gameplan, each music file,whether aac or mp3 will be assigned a random 4 letter code.
Not just that but your iPod won't store any of their descriptive data in any logical format.
This means that all of your music will be transferred to your computer and given names like: zxsr or ftap etc. etc. with no indication for your computer whatsoever of what they are meant to mean. At this point you are going to have to rename them all by ear. If you have sets of albums, iTunes does have an option to name a set of music from that entire album. But it is still a lot of effort.
Overall you might be better off getting some of the software above. otherwise your in for long nights and lots of headaches/screaming.