How to use REST API

I build ScaleIO REST Client.

I succeed  login using "/api/login"parameter,and the login returns token(key) "xxxxx" .

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C# code "HTTP Basic authentication"

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string authInfo = @"admin:password";

authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));

request.Headers["Authorization"] = "Basic " + authInfo;

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but,I don't know use token(key) "xxxxx".

For example,when I  invoke  HTTP GET request using "/api/instances/"parameter,

returns authentication erorr(401) at System.Net.WebException.

C# code

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reqest.Headers["-Auth-Tken"] = "xxxxx";  // "xxxxx" is access_token.

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