Alert box with a textbox and a button..

hi..

I have a button to export data from gidview to excel.On clicking the button,an alert box should appear which contains a textbox and a button named "Generate Report".The textbox is to enter the Filter date from calender control and when we click on the generater report button,the excel sheet should open.Can someone please tell me how can I open the alert box containing textboz and button and how can i write the code for filtering.Should i use javascript or any other Ajax controls.where should i write the code,on server side or client side.I'm new to asp.net,so Please help me..