i purchased some itune music and downloaded worked fine ...plays on my window pc with win. 7, burned a cd for old 2000van ...will not play...plays in my computer and my dvd player...tryed to convert to mp3...no luck with that..at 83 i need help

being 83 yrs old ....i need help on this....I like the way I could purchase and download the music....but I have spent way to much time trying to convert the files to mp3 so as to play I hope when I burn them to a cd to use in my auto....unless I get on here a way to do it...I am going to a different source for music or just buy cd's.....I am using a window pc running windows 7.....thanks...jim