Hi there, timothychu.
I'm here to help start your account in QuickBooks Online.
First, you'll need to subscribe to any version of QuickBooks Online. To do that, please follow the steps below.
1. Go to https://quickbooks.intuit.com/pricing/
2. Select any version of QuickBooks( Simple Start, Essentials, Advanced or Plus).
3. Choose Buy Now or Get a 30-day free trial.
Once done, you can start signing up and enter your email address, mobile number, and password.
You can refer to this article to see everything you need and resources for getting started with QuickBooks Online: Getting started with QuickBooks Online. This article also contains on how to create transactions in QBO.
You can also check this article to see training videos and other resources to help you get up and running with QBO: Video tutorials for QuickBooks Online.
Don't hesitate to post again here in QuickBooks Community. I'm always here to help you.