I can't refence to range in VS 2003 C# office excel project

This code is not work
wsSheet1 = (Excel.Worksheet) ThisApplication.ActiveWorkbook.Sheets["Sheet1"];
Excel.Range myrange = (Excel.Range)wsSheet1.get_Range("A1",Type.Missing) ;

please show me example code

Thank you very much

I can't automate excel

this is my error
"Error: COM object with CLSID {00020819-0000-0000-C000-000000000046} is either not valid or not registered."

help me please
Thank you very much

and
"Error: Exception from HRESULT: 0x800A03EC."

help me please
thank you very much

The problem is probably the way of creating the object instance. You don't create new instances of workbook objects like
you are doing with the line:
ExcelWB = New Excel.Workbook
you open them through the application object. What the error message is telling you is COM can't co-create the workbook object.
Try something like this:

Dim ExcelApp As Excel.Application
Dim ExcelWB As Excel.Workbook

ExcelWB = ExcelApp.Workbooks.Open("File Path")
ExcelApp.Visible = True