I started a business in 2016, where in the software can I claim those expenses

As long as your business was "open for business" in 2016, you will be able to claim the business expenses even if you have no business income.

To enter business income and expenses, once you have signed into your TurboTax Account (for TurboTax Online sign-in, click Here , then select "Take Me to My Return"), type "Schedule C" in the search bar then select "jump to Schedule C".

You would be able to claim any ordinary and necessary business expense that relate to your self-employment business.

This can include such things as any unreimbursed business miles driven to a client or work location, home office expense if you uses a part of your home exclusively for your job and supplies or equipment used in your work to name just a few.

Please refer to this IRS link for more information about Business Expenses