Where do I put in how much money I've lost from gambling at casinos.

[DoninGA]

Gambling losses can only be deducted up to the amount of the gambling winnings. Gambling Losses are reported on Form 1040 Schedule A as a Miscellaneous itemized deduction. Gambling losses are not a one-for-one reduction in winnings. Your total itemized deductions reported on Form 1040 Schedule A must be greater than the standard deduction for your filing status to have any tax benefit.

Gambling losses are entered in the same section as gambling winnings

To enter, edit or delete Gambling Winnings and Losses -

Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Less Common Income
On Gambling Winnings, click the start or update button

Or enter gambling winnings on w-2g in the Search box in the upper right of the program screen. Click on Jump to gambling winnings on w-2g

[Critter-3]

When you enter the winnings the option to enter the losses is in the same place ... you can only take the losses up to the wins and only if you itemize deductions.