Comments by Kwabena Sackey (Top 1 by date)

Thanks they're test credentials but I get the point. I revised the code to read:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(@"https://elig.nhia.gov.gh:5007/api/hp/authenticate/app");
request.Method = "POST";
request.Accept = "application/json; charset=utf-8";

request.Headers.Add("x-nhia-apikey", "xxxxx");
request.Headers.Add("x-nhia-apisecret", "xxxxx");

using (var streamWriter = new StreamWriter(request.GetRequestStream()))
{
string json = new JavaScriptSerializer().Serialize(new
{
GhanaCardNo = "",
UMN = membershipNoTextBox.Text
});
streamWriter.Write(json);
streamWriter.Flush();
streamWriter.Close();
}

var response = (HttpWebResponse)request.GetResponse();

string strResponse = "";
using (var sr = new StreamReader(response.GetResponseStream()))
{
strResponse = sr.ReadToEnd();

}

but I still get 401 unauthorized.