POST using the uploadstring method to call a web service and pass a json array

Question

I am attempting to do a POST to a web service. I am using the WebClient class and calling the uploadstring method. This works fine until the web service I call expects some data, particularly a json array. I am trying to find out what format the data needs to be in, in order for the web service to accept and consume it properly. Example:

WebClient myWebClient = new WebClient();
string resp = myWebClient.UploadString("www.myUrl.com", "POST", "someDataToSend");

Any help here would be appreciated!

the web service (vb.net) being called takes a keyvaluepair:

<OperationContract(), WebInvoke(BodyStyle:=WebMessageBodyStyle.WrappedRequest, Method:="POST", RequestFormat:=WebMessageFormat.Json, ResponseFormat:=WebMessageFormat.Json)> _
Public Function DoSomething(ByVal myKeyValuePair() As KeyValuePair(Of String, String)) As String

Answer 1

I found a solution for this. The data has to be in json format literally:

"{"Type":[{"key":"cType","value":"Age"}]}"

I created a class serialized it and then finagled the square brackets in.

Public Class cType
    Private _key As String
    Public Property Key() As String
        Get
            Return _key
        End Get
        Set(ByVal value As String)
            value = "cType"
            _key = value
        End Set
    End Property
    Public value As String
End Class 

Dim objType As cType = New cType
objType.value = "Age"
Dim myData As String = deserializer.Serialize(New With {.cType = objType})
myData = myData.Insert(12, "[")
myData = myData.Insert(myData.Length - 1, "]")