how do I update iPhoto which tells me that the application is damaged or incomplete. I've never used the application until today.

I see you're running Mountain Lion...how old is your Mac? Do you have the iLife DVD or did you buy iPhoto at the App Store?

A couple of things to try:

• Make sure you run Software Update (Apple menu--> Software Update) to ensure you've got the current version of iPhoto.
• I'm assuming, from your brief description, that you can't successfully even launch iPhoto? If that's the case, you can try trashing the application itself and reinstalling it, either from the iLife DVD or by downloading it again from the App Store.

Will iPhoto launch if you hold down the option key during launch and select Create Newfrom the selections available?

https://discussions.apple.com/community/ilife/iphoto

Your MacBook should have come with iLife11 preinstalled. Assuming the iLife DVD you bought (before you bought your MacBook? Not clear on this) is the same version as what's on your MacBook, you can reinstall iPhoto from the DVD. Just do a custom install and only install iPhoto from it. (And this assumes you've previously trashed iPhoto on your MacBook). Make sure you run Software Update after this reinstall before launching iPhoto to ensure it's updated.

You shouldn't need to reinstall OSX for this issue.

You really should never have a need for the OSX disc unless you get into some SERIOUS issues. Since Lion (we're now on Mountain Lion) Apple no longer provides physical media. The OS can only be downloaded from the Mac App Store.

Should you need to "start over" and load the OS anew, this can be done by booting from the Recovery partition...hold down the "r" key while booting to get to it. (I've never had to use it, but if memory serves, you need to have an internet connection if you're trying to reinstall the OS from the Recover partition).