I Tunes cannot add any songs to the Pod

Hello,
Hi thanks for the info about creating another playlist and then hitting autofill, but I get a message when I do that. It is saying "i Tunes cannot add any songs to the Pod "J Pod" because no songs in the playlist "untitled folder can be copied to this Pod.
Can you please give me other tips to try.
I am not savvy when it comes to computers, so please say it in very layman terms.
Thanks soooo much!