Perhaps something like this may be the least effortful way to get to grips with the very basic aspects of OT? https://www.youtube.com/watch?v=NWNLJxGhLMA

And then this for some more: Book Optimality Theory: An Overview

And this book contains accessibly discussed aspects of different theoretically approaches, including OT: https://www.google.com/search?q=gussenhoven+intro+to+phonplogy&oq=gussenhoven+intro+to+phonplogy&aqs=chrome..69i57.5344j0j4&sourceid=chrome&ie=UTF-8 So this one is nice to put it all in a perspective of phonological theory as such too, in a gentle way.

Hi,

very simply speaking, you assume an input form (underlying representation) and an infinite (but typically very limited) set of output forms. These are typically ordered row-wise in a table. Then there are a set of constraints, which are ordered (the highest ranked one to the left, the lower ranked ones further to the right). These constraints come in two broad classes, faithfulness constraints (that get violated when the output deviates from the input) and markedness constraints (that get violated when the output disobeys general markedness constraints). All constraints can in principle be violated; the winning candidate is the one with the fewest high-ranking constraint violations. Whether and how this framework is useful depends on your research question.

https://pdfs.semanticscholar.org/68a7/3ae53136c0d7141608b0be8bae256ebe5256.pdf .

This may have answers for you