OK, since noone has bothered to give you a simple step-by-step and I'm snowed in here in Seattle, I'll walk you through it. This is a safe method and will leave your original files in tact and on your laptop just in case something happens. Once you've confirmed they are on the external drive you can delete them from your laptop, but I would STRONGLY recommend having a second backup copy somewhere. Hard drives DO and WILL fail eventually.
This is how I'd do it on my Mac. You may want to confirm the procedure is the same on PC, but I think it is.
1. Attach the external hard drive to you computer and format it if it has not already been formatted.
2. Open iTunes
3. Go to iTunes>Preferences
4. Click the "Advanced" tab at the top of the preferences window.
5. Now in the upper part of the window it will show your iTunes music folder location - Make sure "Keep iTunes Organized" is checked, then click the "Change" button to change the iTunes music folder location.
6. Navigate to your external hard drive and choose that as the new location for your iTunes folder.
7. Click "OK" I think iTunes will ask you if you want to move all your music to the new folder (I use a Mac so not sure) - if so click "yes" iTunes should then give you a progress bar that says "updating iTunes library"
8. That's it - iTunes will proceed to copy all the files on your laptop over to your external hard drive. It will leave all the files on your laptop as well in the same folder they were in (Music>iTunes>iTunes Music on my Mac). Again, once you've confirmed they've all been moved to the external you are safe to dump the original files, but, again, I would strongly recommend a backup copy.
If you don't understand any of these instructions or are not comfortable doing them, don't. I've found that the folks at the Apple Genius Bar can be very helpful should you be located nearby an Apple Store. I don't know how much they can help if you are on a PC though, but they do know iTunes.
Regarding the problem you had when you first tried moving files - You must move the files within the program so it can keep track of them. If you just move the files manually outside of the program you are setting yourself up for trouble and that would explain why the files did not show up in the play list.
Hope that helps.
This is how I'd do it on my Mac. You may want to confirm the procedure is the same on PC, but I think it is.
1. Attach the external hard drive to you computer and format it if it has not already been formatted.
2. Open iTunes
3. Go to iTunes>Preferences
4. Click the "Advanced" tab at the top of the preferences window.
5. Now in the upper part of the window it will show your iTunes music folder location - Make sure "Keep iTunes Organized" is checked, then click the "Change" button to change the iTunes music folder location.
6. Navigate to your external hard drive and choose that as the new location for your iTunes folder.
7. Click "OK" I think iTunes will ask you if you want to move all your music to the new folder (I use a Mac so not sure) - if so click "yes" iTunes should then give you a progress bar that says "updating iTunes library"
8. That's it - iTunes will proceed to copy all the files on your laptop over to your external hard drive. It will leave all the files on your laptop as well in the same folder they were in (Music>iTunes>iTunes Music on my Mac). Again, once you've confirmed they've all been moved to the external you are safe to dump the original files, but, again, I would strongly recommend a backup copy.
If you don't understand any of these instructions or are not comfortable doing them, don't. I've found that the folks at the Apple Genius Bar can be very helpful should you be located nearby an Apple Store. I don't know how much they can help if you are on a PC though, but they do know iTunes.
Regarding the problem you had when you first tried moving files - You must move the files within the program so it can keep track of them. If you just move the files manually outside of the program you are setting yourself up for trouble and that would explain why the files did not show up in the play list.
Hope that helps.