What can you do with iTunes?
You can import music from your personal CDs or music files on your computer, purchase music from the iTunes Music Store, organize your music with playlists, burn CDs, transfer music to and from an iPod (portable digital music player), and even share music with others on your network.

Using iTunes
Start by opening the "iTunes" icon on your dock.

 

If this is your first time opening iTunes, you will see the "Setup Assistant."

 

In the "Setup Assistant," you can choose to allow iTunes to search your computer and add all music files to your iTunes Music Library.

 

You can also add music at any time by selecting the music or music folder from your hard drive and dragging it into the iTunes Music Library or by selecting "File" and from the drop down menu "Add to Library."

 

All the music from your iTunes Library is automatically saved to your hard drive. By choosing Advanced and choosing from the drop down menu Consolidate Library, iTunes will organize this music by Artist and Album on your hard drive within your music folder.

Apple has its own article on this which can be found at http://www.apple.com/itunes