Progress bar on Dropdownlist - IMP

Hi all..

I want to put a progress bar for execution of long tasks.

My requirement is-
1. When the Page loads, the user selects an excel file using File Upload Control.
2. Then the user clicks on a button, whose text is - "Get Sheets".
3. On this click event, the system gets the list of sheets from excel (Sheet1, Sheet2, Sheet3) in the dropdownlist.
4.The user selects a particular Sheet from the dropdownlist. (Say Sheet1).
5.The system then updates all the records from excel to sql server.
--------
I want to know the following -
1.Is there any way in which, when the user selects the excel sheet from File Upload Controls, he/she gets the list of excel spreadsheets in the dropdownlist, instead of button ?

2. I want to put a progress bar when the user selects the sheet name from the dropdownlist. How can this be done ?
On selectedIndexChange Event.
------
Progress bar - a .gif round moving image(like sun) with a message "Please wait...".