HttpWebRequest using Basic authentication

System.Net.CredentialCache credentialCache = new System.Net.CredentialCache(); 
credentialCache.Add(
    new System.Uri("http://www.yoururl.com/"),
    "Basic", 
    new System.Net.NetworkCredential("username", "password")
);

...
...

httpWebRequest.Credentials = credentialCache; 

or

httpWebRequest.Credentials = new NetworkCredential("xxx", "yyy","UAT");