I don't understand the lack of Form 1099-B's. What brokerage?
But, why are you asking this "C-Corp" question when the icon next to your name indicates "TurboTax Deluxe", a personal income tax return product? A C-Corp needs to file form 1120 and for that you need "TurboTax Business".
You need the exact same info that you always need when reporting security sales:
A Description of what was sold, the Date of Sale, the Proceeds, the Date of Acquisition, and the Cost Basis, and you need that information for each distinct sale.
