How do I upgrade from snow leopard on a mid-2011 iMac?

Thank you! I can't remember how I finally found it, but the whole trick was finding the "older" OS versions with which to update my older computer. Searching the app store for older versions of OSX doesn't bring up the links you need. For some reason, these things are somewhat "hidden." But I did eventually get everything I needed to bring my machine into the current age! Thanks for helping, though. For what it's worth, I had kept this machine on Snow Leopard because I had some legacy software that had to run in Rosetta. I no longer have the need to use that software, so it was time to get back to the future.