I can't figure out how to gain access to iPhoto v9.3 on my Mac

When I upgraded to Yosemite I did not realize that I would no longer be able to use iPhoto, in which I had sorted my pix into numerous folders. I don't mind Photos but want so much to have access to those folders in iPhoto. I have tried the steps previously suggested in other posts, like going to the app store. Iphoto is not listed as a purchase, I think because it came with the computer. Is there any source of an iPhoto version that I could obtain?