Well there's two problems I see there.

1, I highly doubt your cheapo Goodmans MP3 player will play anything other than MP3, and possibly WMA. So you need to convert the songs from AAC to MP3. You can do this in iTunes. Right click on the song(s) you want to convert and select CREATE MP3 version.

2, you can't drag songs out the library (in iTunes) to put them on an MP3 player (unless it's an iPod/iPhone and you're doing it all within iTunes) You need to drag the "hard" file from it's folder location into your MP3 player. Navigate to the iTunes Music Folder (usually in My Music > iTunes Music > artist folders) and select the MP3's you want (remember to not select the AAC's). Then open the window for your MP3 player, and drag the MP3's into it.