Make a playlist of the music you want and then drag & drop from there – all in one go.
Otherwise, find the files and drag & drop from there. To do his on a Mac, you’ll find that the iTunes Munsic folder (inside the user’s home folder, inside Music, acts a bit odd. What you need to do is right-click on it and choose Package Contnets and then you can see all the files inside…
(It is a .app folder and start iTunes when you open it, automatically. This is also how all the applications work too – try right-clicking on them and having a poke around inside. DON’T change anything!!!)
Rachel