Don't know if this is any good because I haven't used Nero Wave Editor but I have just had a look at it. I have lots of audio tracks in .wav and mp3 format on my hard drive.
I found in Nero Wave Editor. Go to Edit, Insert File. I picked an MP3 file and then Open and there it was in the Editor!
I use LP Recorder to record from vinyl, CD or Cassette to my hard drive: click here