Quarterly payments to the IRS can be done at www.irs.gov/payments. ***PRINT YOUR RECEIPT!!!***. I can't stress that enough.
Typically, if you send the IRS 20% of your gross business income each quarter, then come tax filing time you'll be fine.
If your state taxes personal income, you'll also need to make quarterly payments to your state. How you do that, depends on the state. Not all states allow for online payment. Check your state's website for info.
