MP4 and WMA Files


I have just recently purchased a Sansa e250 mp3 player and it is my first one and I am trying very hard to learn how to use it, but it is much more complicated than I thought it was going to be.

To begin with, I had never heard of tags before I started having problems when I was transferring music to the player. I started with a Playlist and while it didn't copy it as a Playlist, it copied the songs from it over, but some of them didn't have the name of the song or the artist or the album but a number instead even though they all appeared in Real Player, Version 10.5, which I chose to use purposely because it did list the names of everything on it.

After learning more about tags or maybe I should say that there are tags and being told to download the program Mp3tag v.2.37a, I realized that the song that had the number instead of the name was an MP4 file even though it says they are all MP3 files in Real Player. There's also some that say they are WMA files.

However, this is as far as I've gotten. I'm lost from here. Can I convert these files to what I need and if so, can someone please walk me through it?

Thanks so much for any help you can give me. I had no idea there was so much to this and I can see from other posts I've read, I'm only just beginning...