.xsd ordinal

Hi,
Using Strongly Typed dataset, I would like to refer to a column.
This is what I am doing at present:

//dsEmps is the .xsd
EmpBusRule.EmpService.dsEmps employeeDetailsData;

int intEmployeeIDColumn = employeeDetailsData.Employees.Columns[0].Ordinal;
int intFirstNameOrdinal = employeeDetailsData.Employees.Columns[2].Ordinal;

My intention is to use something like :
int intEmployeeIDColumn = employeeDetailsData.Employees.EmployeeID.Ordinal;
int intEmployeeIDColumn = employeeDetailsData.Employees.FirstName.Ordinal;

If I do this the the compiler error is:
'EmpBusRule.EmpService.dsEmps.EmployeesDataTable' does not contain a definition for 'FirstName'

Thanks