string Message_FB = "NOTIFICATION";
var client = new FBClient_Simple(); // or new FBClient() with 2FA handler
string email = "my_email";
string password = "my_password";
// Login with credentials       
bool logged_in = await client.DoLogin(email, password);       
if (logged_in)
{
    // Send a message to yourself
    string myUserId = client.GetUserUid();
    var msgUid = await client.SendMessage(Message_FB, thread_id: myUserId);
    MessageBox.Show("FB Message sent with ID: { msgUid} "); 
}
else
{
    MessageBox.Show("Error logging in.FB { msgUid}                 
}