Welcome to the Community, Renay1.
There are two ways on how you can add the missed public holiday pay.
You may add the missed public holiday pay on your current pay run by selecting Actions button and select Add earnings. Then from the Earnings section, you can select the public holiday pay category.
On the other hand, if you would like to add it on the previous pay run and it has no super on it, you can unlock it and refinalise after you entered the public holiday pay. Then create and lodge an update event.
For more detailed information you can check on this article: Record Public Holiday Pay in QuickBooks Payroll.
Please let us know if there's anything else you need. Thanks.
