Gallery With Downloadable Images In Flash CS3 Web-site

Hello! I have a Flash (CS3) web-site up and running. I would like to add a Gallery page, which has a set of thumbnails. When a thumbnail is clicked, its corresponding large image will appear.
My problem is, that I want this large image to be downloadable – ie, the user right-clicks and selects “Save As” from the menu, chooses a location and downloads the file. I know this can’t be done directly from Flash.
What is the best way to do this?
I can use AS3 but don’t know HTML, etc – but willing to learn.

Any help greatly appreciated.
Or is this feature included in any book or tutorial you know of?

Thank you!