I forgot to contribute my IRA funds, but have already filed and paid.

I did my taxes assuming that we would be contributing money back into our IRA.  I said we would be contributing $7,000 each ($14,000 total) into our IRA prior to April 17th.  I filed the taxes at the end of March, but didn't pay our taxes due until the middle of April.  The tax check has cleared the bank last week.  I just realized (April 23) that I forgot to move the money into our IRA accounts.  I know if I do it now, it will only count again our 2022 year and can not be applied to our 2021 contributions.  

I know this will result in owing more taxes, so how and when do I amend my 2021 taxes?