Do not stress! Your first payment to the IRS does NOT have to go by mail. You can always pay the IRS directly on their website. Also on the IRS website you can view your account balance at any time. Please see the IRS links below for more information and to check on the status of your installment agreement request (Note- the IRS will also send you a letter in the mail once your payment arrangement (installment agreement) has been processed.
https://www.irs.gov/payments
https://www.irs.gov/uac/view-your-tax-account
