It is on 1040 line 6 and subtracted off your total income and reduces your AGI Adjusted Gross Income.
You don't get a refund for losing money. It just reduces your total income so you get taxed on a lower amount. If you were already getting back all that you could a loss won't increase it. And by reducing your income it can reduce any credits you are getting.
2019 Capital Gains and Losses go on Schedule D then to 1040 line 6
And If you have a net loss for the year you can only deduct 3,000 (1,500 MFS) max on your tax return. The rest you have to carryover to next year. You have to report the carryover every year until it's used up. You can't skip a year.
