LifeinAsia - 12:31 am on Jan 25, 2011 (gmt 0)
You don't absolutely need an accountant, but one is *highly* recommended. A good one will recommend how to lower your tax liability by making sure you deduct all legal deductions available to you (and keep you from getting yourself into trouble by taking deductions that you shouldn't). It's pretty much too late for 2010 (although there are a few income lowering issues still available).
How you pay depends on the classification of your business. Unless you registered a corporation or partnership, you will most likely attach Schedule C to your personal tax return.
For where to start, if you decide not to use an accountant (or tax preparer), I suggest you peruse the treasure chest of info available at IRS.gov [irs.gov], paying close attention to the pubs for small businesses.