How can I use a JWT properly, to grant access to restricted REST API calls?

Question

I hope not to be duplicating any question, and also not to be asking something too basic. I´m building a web app in ReactJS, just to get familiar with the framework. I planned to grant access to users using a Facebook login, which I already have working with react-facebook-login. I also have a Spring Boot Rest API, to serve the front-end. But I want to allow access to part of my API just to authenticated users, using the Facebook access token. So in my back-end, I had to do an org.springframework.boot downgrade from 2.0.4.RELEASE to 1.5.10.RELEASE so I can use the Facebook Graph API. Do you guys think this is ok? or should I use a different approach? And to be honest I´m a little confused on how to achieve a correct validation of the user's request on the restricted areas of my REST API using the access token sent from the front-end, Do you guys have any suggestions on this matter?

Thank you all for your help.