First of all thank you for your reply!
I still have a few questions regarding what you said.
I will certainly start working with the backup tool you mentioned once I've got all set up properly.
Right now I'm only trying to backup my whole Library once, then delete everything on my computer and put it back on the computer afterwards. My problem is, as I said, that I've put some parts of my library on my second internal drive, because I didn't have enough storage on my first internal drive....
So right now it looks like that:
Many TV Shows and Movies are on my second internal drive "D"
All other content and the standard library folder of iTunes are located in my internal drive "C" in My Music.
I'm not quite sure I have understood what you mean by a split library and how I have to use it.
For the solely purpose of backing up all my contents once, so that I can delete everything on my computer -
will it be sufficient to simply back up the my standard library in C and the TV Shows, Movies that I have saved in "D"?
If so, how will I be able to import those separated files into the new iTunes?
Also to avoid the storage problem from now on. (Drive D is significantly larger than C). Will I be able to put all my contents on the internal drive "D" after I reinstalled my computer and launch the new iTuens from drive D by holding Shift when starting iTunes for the first time? Will iTunes then use the new location on drive D for all purposes? Because if this would work I could piece all my contents together on Drive "D" in one folder and then simply select this folder for iTunes to work with. (Right now iTunes uses My Music on "C")
Sorry for the complicated wording, it's hard to explain, I hope it was understandable.
Thank you in advance!