Gambling winnings are not directly offset against your losses. Your gambling winnings are included in income in the full amount. Your losses are only usable if (1) you itemize your deductions; and (2) you can only use gambling losses up to the amount of winnings. So if you have $1,000 in winnings and $2,000 in losses, you can only use $1,000 in losses on your return and only if you itemize your deductions.
Enter in your gambling winnings in the Less Common income section and you will then be asked about your losses later in this section.
