如何在asp.net中设置.ashx文件的会话值？

I'm using "jquery.uploadify.js" in my website and this jquery uses an ashx file for uploading images into a folder. In the .ashx, i am using Session["FileNameNews"] for saving images name and i am empty my Session["FileNameNews"] at the beginning of my code. But when i uploading two or three or ... images, each time my Session["FileNameNews"] is empty. I do not want to be empty my session every time I upload a photo and i want the uploaded images to be displayed in a listbox of the parent .aspx page. Other means, i need to my session empty in start of uplaod and fill with images names in end of upload. I am able to upload multiple image at a time.I'm using "jquery.uploadify.js" in my website a