I found a couple of articles that can help you out with syncing playlists to your iPod touch:
Pasted below are some instructions from both documents:
Drag items from the left side of the iTunes window to the pane on the right. To add other types of content, choose a category from the Library pop-up menu.
To add a playlist, select it from the left side of the iTunes window and drag it onto your device in the same way.
Hope that helps,