Thank you for taking the time to contact the Community. I'd be glad to help you with importing the copy of your data into QBO.
Now that you have selected to export a copy of your desktop data, you'll need to log into QBO next. Once you're logged into QBO, click the Gear icon in the top right corner, then select Import Data. There you'll see the question "Need to import QuickBooks Desktop data?," click Find out how.
You'll first need to create a portable company file since you're using QB Desktop 2008.
Let me guide you through on how to accomplish this:
Go to the File menu, then select Create Copy.
Choose Portable company file, then click Next.
Choose the location where you want to save the portable copy.
Click Save, then OK.
Once done, download and install an updated trial version of QB Desktop, then restore your company file. Make sure to log in as the administrator in both QuickBooks Desktop and QuickBooks Online account during this process.