how to create deptwise group when user click on create button and how to save that group in database

Hi
guys
I have
1>1 dropdownlist i.e departmentlist (on dropdown selection userlist will be displayed in checkboxlist)
2> 1 checkboxlist   containing userlist 
3> groupname 
4>create button
So above these things will create group.....
so how to store these in database and what should be database structure because these created group i have to use in another page.
.axpx code
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="add.aspx.cs" Inherits="add" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <he ...