I have a rental apartment because of my business, where do I write that off at

If your additional location is 100% for business, you can right it off under Rent. However, you'll need to upgrade to the Self-employed edition of TurboTax, to enter your rental expenses. The software will prompt you to do this to setup your business, enter general business income and expenses. To add your self-employed businesses and enter your rent expense:

1. Log in and click Take me to my return
2. Click Federal Taxes and then Income & Expenses (If you have the blue button 'Check for more income', click it and then click 'Skip to see all income')
3. Next scroll down to Self-Employment and click Show more
4. Click Start/Revisit next Income & Expenses
5. You'll need to say you're self-employed and add your business. 
6. You'll come to a screen that says Your XYZ Info and on this screen is where you'll enter all income and expenses for your second business.