Récupération d'un token avec OpenID Connect en C#

Bonjour,

J'essaie de récupérer un access_token en dév comme j'arrive à le faire avec PostMan (cf image jointe) pour ensuite grâce à ce token attaquer une api web.
Dans le startup, comment implémenter le ConfigureOAuth ?

public void ConfigureOAuth(IAppBuilder app)
{
//use a cookie to temporarily store information about a user logging in with a third party login provider
app.UseExternalSignInCookie(Microsoft.AspNet.Identity.DefaultAuthenticationTypes.ExternalCookie);
OAuthBearerOptions = new OAuthBearerAuthenticationOptions();

OAuthAuthorizationServerOptions oAuthServerOptions = new OAuthAuthorizationServerOptions()
{
AllowInsecureHttp = true,
TokenEndpointPath = new PathString("/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromMinutes(30),
Provider = new SimpleAuthorizationServerProvider(),
RefreshTokenProvider = new SimpleRefreshTokenProvider()
};

// Token Generation
app.UseOAuthAuthorizationServer(oAuthServerOptions);
app.UseOAuthBearerAuthentication(OAuthBearerOptions);

//Configure Facebook External Login
//FacebookAuthOptions = new FacebookAuthenticationOptions()
//{
// AppId = "841670309262660",
// AppSecret = "8b4eba3df30d4aa95427fa9c90372462",
// Provider = new FacebookAuthProvider(),
// Scope = { "user_about_me", "user_friends", "email", "read_friendlists", "publish_stream", "user_birthday", "user_location" }
//};

//app.UseFacebookAuthentication(FacebookAuthOptions);

OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
{
AllowInsecureHttp = true,
TokenEndpointPath = new PathString("/token"),
AccessTokenExpireTimeSpan = TimeSpan.FromMinutes(30),
Provider = new SimpleAuthorizationServerProvider(),
RefreshTokenProvider = new SimpleRefreshTokenProvider()
};

// Token Generation
app.UseOAuthAuthorizationServer(OAuthServerOptions);
app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());
}

Merci pour votre aide.