如何过帐到salesforce自定义对象？

如何解决如何过帐到salesforce自定义对象？

我正在尝试将信息发布到Salesforce自定义对象，我可以使用邮递员来完成。我已经可以进行GET调用并获取信息了，我已经尝试阅读salesforce REST API，google等。但是我无法弄清楚，但出现400-错误的请求错误。

这是我的代码：

 Dim jsonFields as string="{"Related_Claim__c","a060U0000048UZRQA2"},{"Name","TEST-08182020"}})
    Dim req As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create("https://na123.salesforce.com/services/data/v36.0/sobjects/Letters__c")
    req.ContentType = "application/json"
    req.Method = "POST"
    req.Headers.Add("Authorization: Bearer 00D0U0000009rxm!AQsAQP.08BW_eXhCyx_EcrLmT.h8Ckt4PfmhZSSj7Gro8rV3U3e0.rsdJ1nX6TVMmcePkSunMdmnLf0Zjfl2EglHp392mnsk")
    Dim JsonSerialized As String = JsonConvert.SerializeObject(jsonFields)
    Dim bytes As Byte() = Encoding.UTF8.GetBytes(JsonSerialized )
    req.ContentLength = bytes.Length
    Dim os As System.IO.Stream = req.GetRequestStream()
    os.Write(bytes,bytes.Length)
    os.Close()
    Dim resp As System.Net.WebResponse = req.GetResponse()
End Sub