File a schedule C. You received a 1099-MISC for income earned working, not at a job. You received the full amount and had no taxes taken. This means you need to file the form for Medicare and Social Security taxes that are normally taken from a paycheck. These are called SE, or self-employment taxes.
In addition, you need to add the income to your return. It goes on schedule C for self-employed. You will have to use the Deluxe version or above to add the form. If you want to claim any expenses related to the income, you have to go all the way to the top versions, Self-Employed or Home and Business.