Outlook interoperability

When i declare ,

Microsoft.Office.Interop.Excel.ApplicationClass excel =
         new Microsoft.Office.Interop.Excel.ApplicationClass();

I receive errors as

'Microsoft.Office.Interop.Outlook.ApplicationClass' cannot be embedded. Use the applicable interface instead.

and

The type 'Microsoft.Office.Interop.Outlook.ApplicationClass' has no constructors defined

What is the solution?