How do I upload last year to use carryovers

In TurboTax Online version, if you used TurboTax for 2019 the carryforward should have automatically rolled over.   However if it did not:

In the Online version you have to save your return with all the worksheet as a pdf file to your computer to see the Capital Loss Carry Over and Carry Forward worksheets.

In the Desktop program you can go to Forms and find it in the list in the left column.

You can enter the carryforwards manually.  A loss carryforward, you will need to indicate that you have carryovers from the prior year, and manually enter that those carryforward amounts.