Following is the solution I have implemented. I hope it helps someone.
-- I used HttpClient to make the call and get the token.
Dim client = New HttpClient()
client.BaseAddress = "https://dev-azure.com"
'want the response to be JSON.
client.DefaultRequestHeaders.Accept.Clear()
client.DefaultRequestHeaders.Accept.Add(New MediaTypeWithQualityHeaderValue("application/json"))
'Build up the data to POST.
Dim postData As List(Of KeyValuePair(Of String, String)) = New List(Of KeyValuePair(Of String, String))()
postData.Add(New KeyValuePair(Of String, String)("grant_type", "yourValue"))
postData.Add(New KeyValuePair(Of String, String)("client_id", "yourvalue"))
postData.Add(New KeyValuePair(Of String, String)("client_secret", "yourvlaue"))
postData.Add(New KeyValuePair(Of String, String)("resource", yourvlaue))
Dim content = New FormUrlEncodedContent(postData)
'Post to the Server And parse the response.
Dim responseContent = client.PostAsync("token", content).Result
If (responseContent.StatusCode = HttpStatusCode.OK) Then
Dim jsonString = responseContent.Content.ReadAsStringAsync().Result
Dim responseData = JsonConvert.DeserializeObject(jsonString)
accessToken = responseData("access_token")
End If
End Using