I need to let users send me attached files, which I want to automatically Upload in a IFRAME!

- How can i let a user send file attachments through the use of a simple page??
-Where are these files stored once the user attaches it?
-Can I save the files to my webserver or store them in a SQL database?
-Can I specify where to save these files?
-What formats can I use?

Any help or information will be very helpfull!!!!!!!