How to set MacBook air up as mobile device to sync a portion of music from iTunes?

In itunes, I would like to set my MacBook air up as if it was a portable device. I have lots of music on a desktop pc and would like my MacBook to sync a portion of it. That way, when I'm out and about, I have my latest music with me. Does anyone know how I could do this? I apologise if this is the wrong forum.