string username = "paul@acme.com";
string password = "Just4Rally";
string serverUrl = "https://preview.rallydev.com";

// Initialize the REST API. You can specify a web service version if needed in the constructor.
RallyRestApi restApi = new RallyRestApi();
restApi.Authenticate(username, password, serverUrl, proxy: null, allowSSO: false);

//Create an item
DynamicJsonObject toCreate = new DynamicJsonObject();
toCreate["Name"] = "My Defect";
CreateResult createResult = restApi.Create("defect", toCreate);

//Update the item
DynamicJsonObject toUpdate = new DynamicJsonObject();
toUpdate["Description"] = "This is my defect.";
OperationResult updateResult = restApi.Update(createResult.Reference, toUpdate);

//Get the item
DynamicJsonObject item = restApi.GetByReference(createResult.Reference);

//Query for items
Request request = new Request("defect");
request.Fetch = new List<string>() { "Name", "Description", "FormattedID" };
request.Query = new Query("Name", Query.Operator.Equals, "My Defect");
QueryResult queryResult = restApi.Query(request);
foreach (var result in queryResult.Results)
{
  //Process item as needed
}

//Delete the item
OperationResult deleteResult = restApi.Delete(createResult.Reference);

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.diagnostics>
    <trace autoflush="true" indentsize="2">
      <listeners>
        <add name="RallyRestApiUiSample" type="System.Diagnostics.TextWriterTraceListener
          initializeData="RallyRestApiUiSample.log" />
        <remove name="Defaultlisteners>
    </trace>
  </system.diagnostics>
</configuration>

// Old authentication in constructor
RallyRestApi restApi = new RallyRestApi("user@sandbox.com", "secret", "https://sandbox.rallydev.com", "v2.0");

// New authentication method
RallyRestApi restApi = new RallyRestApi(webServiceVersion: "v2.0");
restApi.Authenticate("user@sandbox.com", "secret", "https://sandbox.rallydev.com", allowSSO: false);