The following example demonstrates enabling a fixed add new record. The AllowAddNew determines whether the user may add records and must be true in order to display the add new record. The AddNewRecordLocation is then used to initialize the placement of the record. In this case, we are setting it to OnTopFixed so that it is always in view.
<igDP:XamDataGrid DataSource="{Binding Source={StaticResource EmployeesDataSource}}">
<igDP:XamDataGrid.FieldLayoutSettings>
<igDP:FieldLayoutSettings AllowAddNew="True" AddNewRecordLocation="OnTopFixed" />
</igDP:XamDataGrid.FieldLayoutSettings>
</igDP:XamDataGrid>