I assume you mean Form 1120S, the annual federal tax return for an S corporation. Even though your business had a loss, you must file the return. In fact, there's a penalty if you don't, even with the loss. You can prepare the return using TurboTax Business.
https://turbotax.intuit.com/small-business-taxes/ For calendar year corporations, the due date is March 15, 2017.
The S corporation will issue you a K-1, and the losses from the business will pass through to your personal return via that form. Please don't enter the business expenses directly into your personal tax return.
You'll also need to file a corporate return for Illinois.
