API-Problem - POST Json-String with httpClient in VB.net - vb.net

Question

I want to POST json values via httpClient into an API. Unfortunately I am quite a beginner and can't handle it.
GET works perfectly:
here the code for GET:
Dim request As HttpWebRequest
Dim response As HttpWebResponse = Nothing
Dim reader As StreamReader
' Wird für https-Requests benötigt
System.Net.ServicePointManager.SecurityProtocol = DirectCast(3072, SecurityProtocolType)
request = DirectCast(WebRequest.Create(url), HttpWebRequest)
response = DirectCast(request.GetResponse(), HttpWebResponse)
reader = New StreamReader(response.GetResponseStream())
Dim s As String
s = reader.ReadToEnd
Return s
But how do I realize POST?
My API-URL looks like this:
https://mydomaine.net/api/auth?token=467445892587458542...
an i will send an JSON-String {"test":"value1":"test1":"value2"}
I've been working on this problem for many hours.
Can someone please help ???

Answer 1

and here is the code that works
Public Function PostRequest(uri As Uri, jsonDataBytes As Byte(), contentType As String, method As String) As String
Dim response As String
Dim request As HttpWebRequest
ServicePointManager.Expect100Continue = True
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
request = WebRequest.Create(uri)
request.ContentLength = jsonDataBytes.Length
request.ContentType = contentType
request.Method = method
Using requestStream = request.GetRequestStream
requestStream.Write(jsonDataBytes, 0, jsonDataBytes.Length)
requestStream.Close()
Using responseStream = request.GetResponse.GetResponseStream
Using reader As New StreamReader(responseStream)
response = reader.ReadToEnd()
End Using
End Using
End Using
Return response
End Function