You can move your entire iPhoto library to a different computer, a hard disk, or another location on your computer.
Important: Before you move your iPhoto library, it’s a good idea to back it up to a DVD or external hard disk.
To move your iPhoto library:
If you’ve created multiple photo libraries, be sure to move only the library currently displayed when iPhoto is open. To move a different library, you first need to switch to it.
In the Finder, choose your home folder (it’s usually named after you).
Open the Pictures folder (in the home folder) to locate the iPhoto Library file.
Drag the iPhoto Library file to a new location on your computer.
In the window that appears, select the library you want, and then click Choose.