Old time user (v2.2 era) is back and confused with adding files into Library

[prscustom]

Hi guys,

My last update was v2.2 years ago. And now that I have new Windows 10 system, I upgraded Musicbee with the latest version.

I managed to add existing collections which are dispersed in three different hard drives.
But now I'm having a difficulty to add up new mp3s into library.

I just want my new files added to library 'and' transferred to one of thos hard drives.

What should I do?

I thought I can just move my current library to 'that' hard drive, but it doesn't work.
It won't even allow me to change library. (error message shows up.)