I did backdoor Roth contribution for 2024 last week, by depositing to Trad'l IRA and transferring to Roth a few days later (Fidelity). Do I report this as Trad'l or Roth?

You will enter a Traditional IRA contribution and make it nondeductible. You will have a 2024 Form 8606 with a basis on line 14, which will be carried over to your 2025 return. The conversion will be entered next year on your 2025 return.

Please see How do I enter a backdoor Roth IRA conversion? for detailed instructions.