If you are using TurboTax Online, select
Deductions>Additional Dependant Information from the left side menu.
If you are using TurboTax CD/Download in EasyStep
Mode, select Introduction>Dependants from the left side menu. Then click the
Enter New Dependant button to add a new dependant, or EDIT next to a dependant
to add info such as their Net Income.
If you are using TurboTax CD/Download in Forms
Mode, click on the Dependant button on the blue icon bar.