If you are using the OAuth Resource Owner Password Credentials security policy, you must already have registered your client application to complete the necessary fields on the Connections page.

Before a client application can request access to resources on a resource server, the client application must first register with the authorization server associated with the resource server.

The registration is typically a one-time task. Once registered, the registration remains valid, unless the client application registration is revoked.

At registration time, the client application is assigned a client ID and a client secret (password) by the authorization server. The client ID and secret are unique to the client application on that authorization server. If a client application registers with multiple authorization servers (for example, Facebook, Twitter, and Google), each authorization server issues its own unique client ID to the client application.

@ref: http://tutorials.jenkov.com/oauth2/authorization.html

For OAuth configuration, read the provider documentation carefully and provide the relevant values.