How to call API URL in asp.net c#

string url = "{url}"; 

string param = "name value pair data";
System.Net.WebClient webClient = new System.Net.WebClient();

string encoding = "application/x-www-form-urlencoded";

webClient.Headers[System.Net.HttpRequestHeader.ContentType] = encoding;

string res = webClient.UploadString(url, param);