Hi @shipscat21,
I've got your back on your query, and I'll walk you through how you can import bank transactions in QuickBooks Online (QBO).
The first thing you need is to visit your online bank's page, then download those missing transactions as a CSV file. Take a look at this article that has a detailed guide on this process: Manually upload transactions into QuickBooks Online.
Right after, you can refer to this article: Reconcile an account in QuickBooks Online. It's a detailed step by step guide on how you can reconcile your bank transactions. It's so you can ensure your books remain accurate.
Direct other questions you have to the comments below. I'll get back to you as soon as I can.