iPhoto not launching after upgrade to Yosemite, I don't know how to execute the fix

I migrated a MacBook pro to a new iMac with Yosemite. I then upgraded iPhoto to v 9.6, and when I try to launch iPhoto, it does not launch, stating: iPhoto cannot be opened because of a problem.

I found the fix to the problem on a related question on this site that references: http://ift.tt/1x7ki9b

This appears to address my issue, based on the error report. I've downloaded the replacement file, but I don't know where to put it. I don't seem to have a /library folder. Where should I be looking? Finder will not let me create a /library folder either.