Restoring your 2008 backup file directly to QuickBooks Desktop 2019 will likely cause data damage or loss, zoelunn.
We always recommend restoring your backup file an an incremental order. For example, you'll restore it to QuickBooks Desktop 2009 and create another backup copy. Then, do it again on a higher version until you reach the latest one.
Since the earlier versions of QuickBooks Desktop are no longer available in the download page, I'd recommend reaching out to our Technical Support Team. They can help you restore your backup file to earlier versions.
You can also use this link to reach them outside QuickBooks: https://help.quickbooks.intuit.com/en_GB/contact.
Once your backup file is already on a supported version (QuickBooks Desktop 2017 and later), you can convert it to QuickBooks Online. Here are the process that you need to follow:
You can use this article to see the details steps of the process: Convert QuickBooks Desktop File to QuickBooks Online.
I'll get back to you if you have follow up questions about this.