you would use form 6252 to report the installment sale.
however, I would suggest talking to a tax pro.
we know nothing about the C-Corp or your tax situation.
at the worst the C-Corp would have capital gain when it receives each installment and owe income taxes on it.
then if the net cash is distributed to the shareholders they will have dividend income and may owe a tax on that. if the corp retains the cash and invest insecurities it might become a personal holding company which has other tax consequences.
liquidating the corp might minimize the income taxes but again we know nothing about the corp or your tax situation. professional advice should be sought.
