如何在flex 3中创建和使用弹出窗口？

I have used a datagrid and one button in control bar. by clicking button the application goes edit state from base state. My question is how can i use popup for editing selected record of datagrid instead of changing state. please give me any example with code that describe how pop ups can be used in flex 3 application.I have used a datagrid and one button in contro