I follow the way like https://developer.paypal.com/docs/classic/permissions-service/integration-guide/PermissionsUsing/
I am able to get grant access as token, signature & timestamp. But here is no specified API to get basic information.
To generate the authentication header X-PAYPAL-AUTHORIZATION you need to use the Permissions SDKs provided in the link you linked.
At the end of the Permissions Integration guide it advises on how to use the authorization after it's been generated.