I'm helping my son file his taxes for the first time, where does he apply for the recovery rebate/stimulus when filing? I didn't see any box or section for it.

[Critter-3]

• After you have entered your tax information and are ready for the Federal Review, stimulus will be the first question.
• If you are trying to trigger it: 
1. go to Other Situations
2. click Done. 
3. The next question will ask about payments received.
• The program will determine the missing amount and add it to your refund.

Please see: Is My Second Stimulus Check on the way? and the IRS stimulus website