I think I lost my photo library! Please help me!

Where is the Aperture photo library? I'm starting to think I've lost all my photos.

I have an older copy of Aperture on an iMac running Snow Leopard. I got it from a friend, and not from the App Store. My mac failed so I got a new one that arrived yesterday. It came with Yosemite installed. I migrated my data from the old mac and the Aperture app showed up as a broken app. When I look in my Pictures folder, I don't see the Aperture photo library. My old mac's internal drive is still ok but the mac won't boot up to a usable display (I think the logic board is bad).

If I launch Photos in Yosemite, it doesn't seem to find that I have Aperture or iPhoto (to allow me to import).

Someone please walk me off the ledge here. What should I try? I have another mac (mac mini) on my network, that is still running snow leopard. Is there a way to copy the app from the other mac (by dragging it over to the mini)? What else would I need to move over to get this working?

Thanks in advance.