Thank you for posting to the QuickBooks Community, @feimin-koo-archl. I'll share information about how you can set up your Chart of Accounts for a demo company.
 
Once set up, QuickBooks automatically creates your chart of accounts for you. If you need to add additional accounts, you can create them manually. 

You can also practice with sample client companies. This way, you can use the tools with a sample of complete data. 

To learn more about the chart of accounts in QuickBooks, you can click here. This will guide you through your company's accounts and their balances.

Don't hesitate to leave a comment below if you have other concerns about the demo company. I'd be glad to help you. Have a great day.