After downloading Form 8949, there are several steps to upload the file and add it to the TurboTax tax filing. First, go to the "Federal" tax filing section and select the "Wages & Income" tab. Next, click "Add more income" and select "Investments and Savings" from the dropdown. Then click "Start" next to "Stocks, Cryptocurrency, Mutual Funds, Bonds, Other (1099-B)" to upload the Form 8949 file from the computer. TurboTax will then display the investment sales summary and require verification of all digital asset disposals during the review phase.