Hello there, @Emma4u.
Thanks for visiting the Community. Let's sort this thing out together so you can start your first reconciliation.
All you have to do is to click the Edit info button so you can enter the ending balance and date as it's written on your bank statement. Once done, review and compare each transaction on your bank statement. Then, put a checkmark next to the amount in QuickBooks if they match.
Here's an article for more detailed guidelines: Reconcile an account in QuickBooks Online. It also contains a quick video tutorial to guide you through the process.
Just in case you'll encounter any reconciling issues, refer to this help article: How to fix opening balance issues.
Feel free to visit again and leave a comment below if you need further assistance. We're always around to assist you more.