How do i put songs onto an mp3 player from the itunes site?

I have a generic MP3 player by Coby and I do NOT know how to use it! It was given to me and already has music on it and I don't have any instructions on how to use it. I don't know how to access what is in there, how to get it out (not the kind of music I listen to) or how to load more music on. Can someone please help me? I am a techy idiot! lol Thanks in advance for all serious replies!