Problem with iTunes

I had all my music saved to my iPhone 6 but didn't realize it was not part of my backup. So, I had to recreate it when I got the iPhone X. I used windows media player to rip my cd files to mp3 on my notebook. Then in iTunes I "Added a Folder" which took the all the songs except the first. It then saved that first song to an unknown artist folder with an unknown song title. As a result, almost all my albums are missing the first song. How do I fix that?