If you need to prepare a Form 1120-S for an S corporation, you need TurboTax Business (link below) which is not available online or for a Mac; it must be installed and run in a Windows environment. Further, TurboTax Business can only be used to prepare income tax returns for entities; it cannot be used to prepare an individual income tax return (e.g., Form 1040).
https://turbotax.intuit.com/small-business-taxes/
Finally, if you are not extremely familiar with the rules and regulations that relate to S corporations, you should definitely seek professional tax guidance and assistance with return preparation rather than attempting to do it yourself.
