There are many ways. Via Network file transfer, Optical Media, Flash Drive, External Hard Drive. If you use an external drive or flash drive, just copy the itunes folder if it will fit to the external drive and drop them into iTunes on your Macbook and have it set to make a copy to the iTunes folder.
If some of your music is the older Apple ITMS store songs with DRM, you can activate up to 5 computers to play the songs. Be sure to do that with the Macbook. The new DRM free songs and any you ripped off your own CD's won't have that issue.
If you need more of an explanation and where the music is, let us know.