The instructions for F.8915-E, which has yet to be finalized, and materials published by the IRS should be your guide, if you prefer not to read up the Act and the Code.

In terms of input, that's under Income > Pensions, IRAs (1099-R) on the Less Common Scenario tab.

https://www.irs.gov/newsroom/coronavirus-related-relief-for-retirement-plans-and-iras-questions-and-...