How to call Non-static method from server without postback?

public static string GetCurrentTime(string name)
{
   ClassToBeUsed c = new ClassToBeUsed();
   return c.NonStaticMethod(); 
}

[System.Web.Services.WebMethod]
    [System.Web.Script.Services.ScriptMethod]
    public static object GetUploadStatus()
    {
        //Get the length of the file on disk and divide that by the length of the stream
        UploadDetail info = (UploadDetail)HttpContext.Current.Session["UploadDetail"];
        if (info != null && info.IsReady)
        {
            int soFar = info.UploadedLength;
            int total = info.ContentLength;
            int percentComplete = (int)Math.Ceiling((double)soFar / (double)total * 100);
            string message = "Uploading...";
            string fileName = string.Format("{0}", info.FileName);
            string downloadBytes = string.Format("{0} of {1} Bytes", soFar, total);
            return new
            {
                percentComplete = percentComplete,
                message = message,
                fileName = fileName,
                downloadBytes = downloadBytes
            };
        }
        //Not ready yet
        return null;
    }

PageMethods.GetUploadStatus(function(result) {
            if (result) {
                setProgress(result.percentComplete);
                //Upadte the message every 500 milisecond
                updateMessage(MessageStatus.Information, result.message, result.fileName, result.downloadBytes);
                if (result == 100) {
                    //clear the interval
                    window.clearInterval(intervalID);
                    clearTimeout(subintervalID);
                }
            }
        });