How to add itune music to a RCA mp3 player?

okay so I just bought 2 songs off of itunes and now I want to add it to a mp3 player by RCA. i go to windows media player (cause I can't add it from itunes because it needs to be a ipod) I go to other media and I put the songs on the sync list then start sync. I put it on there but now I can't find it on my mp3 player and it says the music is already on the device.