I need to update iPhoto for OS X Yosemite but it is not available in the Apps store.

I cannot open iPhoto. The message I get states my current version of iPhoto is not compatible with OS X Yosemite and directs me to update my version through the Apps Store. When I try that, I get a message that the app is not available in the US. What is up with that and how do I download a compatible version??