You would enter it under the option for "Additional income and other income" - this is basically a line for general income that isn't reported on a Form 1099-MISC. It will get totaled to Line 1a of Schedule C for "gross receipts or sales not reported on a 1099-MISC," which, in turn, will get totaled with any 1099-MISCs for total gross receipts and sales.
After you enter your income, you will be prompted with a list of expenses. This year TurboTax is more interactive and it will suggest different expenses that you might have based on your business description. You will want to make sure you fill out the Inventory section for a retail sales business, but I'd also recommend checking the full list by selecting "Less Common Expenses" after you are done with all the recommended expenses.