To claim your Capital Gains from sale of stocks, using TurboTax Online, click on Income > Investments > Capital Gains & Capital Gains Deduction Profile. Check the box "Sold stocks, bonds, real estate, other capital property, or sold qualified small business corporation shares and/or qualified farm property and you have a capital gain or loss to report" and continue to the Capital Gains page, where you can complete the information.
For any Capital Losses you have, go to Deductions > Losses Profile > Net Capital Losses Carryforward. Check the box "Net Capital Losses" and continue to the Net Capital Loss Carry Forwards page where you will be prompted to complete the information shown on your NOA.