Hey @night,
Thanks heaps for your help. That worked. Your a legend
I have changed my code to the following for anyone else they may need help:
string URIForAuthCode = "https://api.twitch.tv/kraken/oauth2/token";
List<KeyValuePair<string, string>> paramListForAuthCode = new List<KeyValuePair<string, string>>()
{
new KeyValuePair<string, string>("client_id", clientId),
new KeyValuePair<string, string>("client_secret", clientSecret),
new KeyValuePair<string, string>("grant_type", "authorization_code"),
new KeyValuePair<string, string>("redirect_uri", redirectUrl),
new KeyValuePair<string, string>("code", codeFromResult)
};
var httpClient = new HttpClient();
var responseFromPost = await httpClient.PostAsync(new Uri(URIForAuthCode), new FormUrlEncodedContent(paramListForAuthCode));
string content = await responseFromPost.Content.ReadAsStringAsync();