Hi Andrew -
You can export the old Test Cases into a CSV file, then import the CSV file in to the new Test Library.
However, you need to carefully look at the old Test Cases and determine how your Steps are typically defined. Our support team can help you set up the import the right way to either create one large Test Step, or split the old Steps into multiple steps by line break.
If your old Steps use some other formatting - ordered order numbered lists, for example - we may need to set up a conversion of some sort for you.
This information might help you:
Importing and Exporting Tests in the Test Library.
If you need any assistance, please let our support team know - just click on the Help Center link right in the application, then Create Support Ticket.