It is best to enter the information from your W2-G (not from your casino win loss statement) and then enter your losses on Schedule A.
The following rules apply to casual gamblers who aren't in the trade or business of gambling. Gambling winnings are fully taxable and you must report the income on your tax return. Gambling income includes but isn't limited to winnings from lotteries, raffles, horse races, and casinos. It includes cash winnings and the fair market value of prizes, such as cars and trips. For additional information, refer to Publication 525, Taxable and Nontaxable Income, or review How Do I Claim My Gambling Winnings and/or Losses?
A payer is required to issue you a Form W-2G (PDF), Certain Gambling Winnings, if you receive certain gambling winnings or have any gambling winnings subject to federal income tax withholding. You must report all gambling winnings on your Form 1040 (PDF) as "Other Income" (line 21), including winnings that aren't reported on a Form W-2G (PDF). When you have gambling winnings, you may be required to pay an estimated tax on that additional income. For information on withholding on gambling winnings, refer to Publication 505, Tax Withholding and Estimated Tax.
You may deduct gambling losses only if you itemize your deductions on Form 1040, Schedule A (PDF), and kept a record of your winnings and losses. The amount of losses you deduct can't be more than the amount of gambling income you reported on your return. Claim your gambling losses up to the amount of winnings, as an "Other Miscellaneous Deduction" (line 28) that's not subject to the 2% limit.
If you're a nonresident alien of the United States for income tax purposes and you have to file a tax return for U.S. source gambling winnings, you must use Form 1040NR (PDF), U.S. Nonresident Alien Income Tax Return. Refer to Publication 519, U.S. Tax Guide for Aliens, and Publication 901, U.S. Tax Treaties, for more information. Also, nonresident aliens of the United States can't deduct gambling losses.
To deduct your losses, you must keep an accurate diary or similar record of your gambling winnings and losses and be able to provide receipts, tickets, statements, or other records that show the amount of both your winnings and losses. Refer to Publication 529, Miscellaneous Deductions, for more information.