Hi,
To Upload or Download a file using flash in web applications use "FileReference" class.
The FileReference class provides a means to upload and download files between a user's computer and a server. An operating-system dialog box prompts the user to select a file to upload or a location for download. Each FileReference object refers to a single file on the user's hard disk and has properties that contain information about the file's size, type, name, creation date, modification date, and creator type (Macintosh only).

FileReference instances are created in two ways:

When you use the new operator with the FileReference constructor: var myFileReference = new FileReference();
When you call FileReferenceList.browse(), which creates an array of FileReference objects

Thanks

A.Ramesh