I'm trying to report taxes paid by my S-Corp on form 1120S. Where do I find the amount my company paid in SS & Medicare taxes?

I am not sure I understand the question. Payroll taxes paid for employees are reported on line 12 of the 1120S (as are other taxes and licenses).

If you are asking because you are trying to fill in your 1120S, look to see what you sent to the IRS using form(s) 941, lines 5a through 5d, in column 2.

Yes, that's right, but I think half of the amount from 5a & 5c was paid by the employee and deducted in my payroll area of 1120S, so do I take 50% of the amount of lines 5a & 5c and add that amount to line 12 on 1120S?

Good catch. Since the instructions for line 8 say "Enter on line 8 the total salaries and wages paid or incurred to employees (other than officers) during the tax year", the employee's part of FUTA is already listed there as a business expense. Therefore, you would list your half of the FUTA taxes actually paid (which will be both your contribution and the employee's) on line 12, so that there would be no double deduction.