'Sharon's Limewire Tunes' is just a playlist. Those files aren't in the iTunes library, that's why you can't transfer them to your iPod. You'll need to add files from LW's saved folder to the iTunes library.

In LW, tools > options > saving will show you the location of your saved folder. If you go to LW's library, highlight a song & click Explore...your saved folder will open. Add files to the iTunes library from this folder

There's lots of info here.
Transferring music to iPod & iTunes