Hi @terren!
This question isn't a great fit for the User Support category. I've moved it to General Discussion. Please take a glance at this post about what posts should go in which category. This information is also included in the category selection dropdown when you go to create a new topic.
Here's a great post from a community member that briefly discusses most of the diversity measures available in QIIME 2. It includes references to primary sources, which are worth reading so you can get a feel for how these methods are intended to be used. It may take a little while to digest, but is worth the time invested.
I'm not very good at reading and interpreting mathematical formulas myself, so I can really empathize with you on how hard it can be to get started with this stuff. With the older and more common measures, like the ones you're looking at, you might want to try googling again, looking for applied examples. I haven't saved any bookmarks (sorry!), but lots of university (e.g.) and private sites have introductions to common diversity measures that are easier to start with than the primary source material.
Best of luck,
Chris 