Accessibility guidelines for powerpoint

Hello,

Hi! I am an employee of a community college and we are trying to update our
website so that anyone and everyone can use it. I am currently trying to
update our PDFs and encountering things that aren't quite covered in most
of the material that I'm finding. Do you have any pointers on where I could
find some good intel?

If you're curious: Someone has copied powerpoint slides into the end of the
PDF as separate images and I'm not sure if I should add alt text to narrate
or slice off the powerpoint, then attach it at the end and properly make
that accessible.

Thank you for your time,

Laurie Kamrowski-Lamb