I lost my iTunes library?

Question

(Apologies if I'm posting this in the wrong forum.)
First off, I have a Macbook 6.1, version 10.6.8. and iTunes version 11.4 (18). Originally, I was attempting to put my iTunes library onto my external hard drive to save space on my computer. Here are the steps that I took:
1.) I made a copy of what I thought was my iTunes library. My iTunes library somehow is a "Previous iTunes Library" (which happened maybe 3 years ago, but I don't remember how), and in Finder there were multiple items called "iTunes Library (various dates)" so I picked the one that looked like the most current date. However, I have reason to believe I chose the wrong file, which I will explain later.
2.) After copying what I thought was my current iTunes library, I put it on my external hard drive.To make sure that the one stored on my external hard drive opened each time I used it, I held down alt/option when launching iTunes and clicked on the one I copied (I knew it was the copied one because I changed its name to  "iTunes Libraries Copy"). However, when I opened this copied iTunes, I realized it was the wrong one (a previous iTunes library with only about a third of my music).
So my current problem is that I can't locate where my current iTunes library is. It's got got to the point that I just confused myself so badly that I've just kept the old iTunes as the one that opens. If at all possible I would like to find the iTunes library that I had before this whole mess happened. I've tried opening all the files called "Previous iTunes Libraries" in Finder and none of them are the right ones somehow. Essentially, I lost the file of the iTunes library that I want, and I want to find it again.
Also, if this matters, I still have the iTunes library I want on my iPod touch (because I haven't synced it). Additionally, I had backed up my computer (including, I assume, the iTunes library I want?) using Time Machine, but I'm  fairly new to that and I'm not sure how to retrieve it. Whatever is the simplest method to get my iTunes library back would be great! I'm trying to free up space on my Macbook so I can purchase a Macbook Air and transfer all my stuff (minus the stuff that takes up way to much space, such as iTunes). I realize this is quite confusing, but I would appreciate any help I can get!

Answer 1

Well, put it this way, this is what you should have done: Moving a library: Quick answer if you use iTunes' default preferences settings: Copy the entire iTunes folder (and in doing so all its sub-folders and files) intact to the other drive. Hold down the option (alt) key (shift on Windows) and open iTunes. At the prompt to create or choose a library choose the copied iTunes folder.