How can I add versioning support for your REST API's ?

[sundarsabapathi]

I am new for REST APi's. I am using your project to learn the API's .I am trying to add versioning support for REST API's in your project. I choose custom header approach to define the versioning for the API's. But i stuck if suppose you made breaking changes in any of the REST end point and you introduce the new version for endpoints. Can i use the latest version to access to all the endpoints or I need to access the specific endpoints using newer versions. Can you please help me to give some ideas it will be helpful for my learning ?