hi, i have seen most of the time we require Automation process in .net
programming, Automation is a process that permits applications that are
written in languages like C#, classic asp, vb.net to control other
applications.like creating new Workbook, Store the result into excel file , desing a chart and so many. You can do this manually also and

programetically also by using AUTOMATION

in C# we have an Application object, a Workbook object, and a Worksheet

object, each of which contain the functionality of those pieces of Excel.
but for that we have to set the proper project reference to the Excel type

library in C#.

Steps to Create an Automation Client for Microsoft Excel.

1. Create new Project , select Windows Application from Visual C# Project types.



2. on Project menu , click the add refrence



3. click on COM tab ,locate Microsoft Excel Object Library, and click Select.



4. click ok to add References

Creating sample automation example:

1. add a Button to form1 and double-click on button1.
2. it will create this code

private void button1_Click(object sender, System.EventArgs e)
{
}

3.include excel directive on you’r page
using Excel = Microsoft.Office.Interop.Excel;
4.now create object for workbook, worksheet and application also.
//this will Start Excel and get Application object.
Excel.Application XL = new Excel.Application();

//Create new workbook
Excel._Workbook WB;
WB = (Excel._Workbook)(XL.Workbooks.Add( Missing.Value ));

Excel._Worksheet WSheet = (Excel._Worksheet)WB.ActiveSheet;

5. Now you can add data into excel file. you can select one cell
and with the help of that add new record with same.
like :
WSheet.Cells[1, 1] = “ID”;
WSheet.Cells[1, 2] = “Password”;
6. if you want to set the field as a bold
WSheet.get_Range(“A1″, “B1″).Font.Bold = true;
7. now u can add records on that.
string[] Result = new string[1,2];

Result [0, 0] = “Kiran”;
Result [0, 1] = “Automation”;
8. it will fill the records.
WSheet.get_Range(“A1″, “B1″).Value2 = Result;

9. now save you’r work and close excel
WB.SaveAs(nameoffile, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value,
Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, Missing.Value, Missing.Value, Missing.Value, Missing.Value, null);
WB.Close(false,nameoffile, Missing.Value);

Known Issues with Automation

Because the CLR uses a garbage collector for memory management, and because your RCW is itself a managed object, the lifetime of your Automation object is not guaranteed to end.you can get the actual help from here

317109 : Office Application Does Not Quit After Automation from Visual Studio .NET Client

Hope it will help you.
Thank You,