HTTP Request in C# using WebClient

I'm trying to get the contents of a folder for downloading from Dropbox in C# using the HTTP libraries. So far I've been trying to use a console application project in Visual Studio but don't seem to be making alot of headway.

What I would like to do is A) See if there are files in the folders and then B) download then to a location (in this case a SharePoint library but I can't seem to make the initial connection using .Net 3.5

Code sample so far:

        static void Main(string[] args)
        {

            using (WebClient client = new WebClient())
            {
                var URI = new Uri("https://api.dropboxapi.com/2/files/list_folder");

                client.Headers.Set("Content-Type", "application/json");
                client.Headers.Add("Authorization", "Bearer <MyApplicationAccessToken>");

                // data
                var reqparm = new System.Collections.Specialized.NameValueCollection();
                reqparm.Add("path", "/<MyApplicationFolder>/");
                reqparm.Add("recursive", "false");
                reqparm.Add("include_media_info", "false");
                reqparm.Add("include_deleted", "false");
                reqparm.Add("include_has_explicit_shared_members", "false");
                reqparm.Add("include_mounted_folders", "true");
                byte[] reqBytes = Encoding.ASCII.GetBytes(reqparm.ToString());

                byte[] responsebytes = client.UploadData(URI, "POST", reqBytes);
                string responsebody = Encoding.UTF8.GetString(responsebytes);
            }
        }

Any ideas? Cant use the .Net SDK