To authorize an API request, set the value of the Authorization header to the Base-64 encoded value of your application's OAuth credentials.
Before encoding the credentials, combine them by listing the client_id value, a colon, then the secret value.
In other words, Base64 encode the following: <client_id
>:<client_secret
>
For the Authorization header value, precede your B64-encoded credentials with the word "Basic "
and a space, as demonstrated here:
Basic <B64-encoded_oauth_credentials>