A good way to make sure something added to iTunes library does not "get lost" in your iTunes library is to create a new playlist in your iTunes library. You can call it something like Import (or whatever you want). Show it using the Songs view (plain song list with columns).
To add a song to iTunes library, open a Finder window showing the song files (or the folder containing the song files). Drag the song files or folder from the Finder window and drop on the iTunes window, on the Import playlist. The song is added to your iTunes library AND to this playlist, so you can see it on the playlist, and edit the song's information as desired.