If you run all the interview steps in order, you should be asked about estimated payments. If you skip around, it's up to you to find that section.
You may not have to file an amended return. The IRS knows you made estimated payments and may add them to your refund automatically. Wait for your first refund to be paid and see what happens, and if you aren't due a refund because you left off the estimates, you might want to wait a few weeks and see if you automatically get a check.
