Jquery - Iterate Through JSON Object List Provided By Webservice?

I have an ASP.NET webservice method that returns a generics list (List'<'Construct>) serialized as JSON, using code such as this:

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
public class TestService : System.Web.Services.WebService {
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string GetOccupationListJSON(int SOCLevel)
{
Construct NewConstructList = new ConstructList();
DataContractJsonSerializer serializer = new DataContractJsonSerializer(ConstructList.GetType());
MemoryStream ms = new MemoryStream();

[Code]....

I assumed (from looking elsewhere) that accessing the JSON data through the index would provide me with access to the underlying object at that index, so that I can then work with it to access its properties.
However, when i=0 and I do var Construct = data[i]; I get the character at the i position of the data array ([), and in the next iteration I get the second character ({). So clearly I am accessing the elements of a string array rather than the JSON data object.How do I make sure that the data returned by the webservice gets into proper JSON format, so that I can iterate through the object elements within it?