$(document).ready(function () {
    //Set the number of sheets to 3.
    var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"),{sheetCount:3});

 $("#button1").click(function(){
         // Create a new sheet and add it at 2nd position.
         var sheet = new GC.Spread.Sheets.Worksheet();
         sheet.name("The added sheet");
         spread.addSheet(1, sheet);
     });
});