Download the iPhoto upgrade from the App Store. It should be free.
iWork and iLife for Mac come free with every new Mac purchase. Existing users running Mavericks can update their apps for free from the Mac App Store℠. iWork and iLife for iOS are available for free from the App Store℠ for any new device running iOS 7, and are also available as free updates for existing users. GarageBand for Mac and iOS are free for all OS X Mavericks and iOS 7 users. Additional GarageBand instruments and sounds are available for a one-time in-app purchase of $4.99 for each platform.