You don't have to worry if you only have the Online version, @mike304. You've got my back to help you resolve this.
You can use the Desktop trial version and from there. Before you start, make sure your computer meets the minimum requirements to install QuickBooks.
You just have to click the link you want to use. Save the install file somewhere you can easily find it, like your Windows Desktop.
QuickBooks Pro 2021
Use these codes to install QuickBooks Pro 2021 trial:
QuickBooks Desktop Enterprise 21.0
QuickBooks Mac 20201
From there, export your transactions to QuickBooks Online. Here's how:
For more information, feel free to check out this article: Import from QuickBooks Desktop and other software to QuickBooks Online.
You also have the option to manually import bank transactions to your QuickBooks Online.
Know that you're always welcome if you have other concerns. I'll make sure to help you out. Have a blessed day.
Which QB Desktop year and country version did you have when creating the backup file?