Filed a extension on Wednesday last week would like to pay something towards what I owe

You can pay directly via the IRS website which is the recommended way or you can pay by check.  Be sure to include your SSN on your check and the tax year. 

If you decide to mail a check, it must be mailed today.  Get proof of mailing (registration).

If you can't pay your whole bill now, pay as much as you can by the end of the day today, as that will reduce any future interest or penalties.