You can use one of the following:
IRS Payments: https://www.irs.gov/payments
EFTPS: https://www.eftps.com/eftps/ (requires registration)
Form 1040-ES: https://www.irs.gov/pub/irs-pdf/f1040esn.pdf (you can print out these forms using TurboTax, but you must mail the vouchers with payment).
[also, note the due dates on the Form 1040-ES vouchers]
