Hopefully you already itemize your deductions on your taxes. When you itemize, you can deduct gambling losses up to the amount of your winnings. I'm not a tax expert, but if you won a couple thousand, I would deduct the whole amount. I can't see anyone at the IRS not believing that someone would have a couple thousand in losses to offset winnings. If it was more than a few thousand, that gets tricky.
If you take a standard deduction on your taxes, then you wouldn't be itemizing in order to deduct your losses.