Hi rrboutique11-out,
Welcome to the Community! QuickBooks is a versatile program that enables you to get your work done faster. I can guide you through how expenses work in QuickBooks Online so that you can consider how you might go about recording your gas expenses.
QuickBooks Online keeps expenses simple with the types of expense transactions available and the ability to set up expense accounts in your Chart of Accounts to use on your forms. Setting up your fuel expenses could be a simple as setting up an expense account in the Chart of Accounts and then recording your expenses against it. I've got a couple of articles that can help with setting up accounts and then creating expenses.
If you're concerned there might be a specific way you should be recording this kind of transaction, I recommend consulting the CRA or an accountant. The CRA website may have useful resources for how you'll need to consider these transactions, and it never hurts to have an accountant on your side.
You can even work with an accountant right in your books. The My Accountant tab has a field where you can invite an accountant on as a user and it also has the Find a pro to help button that you can use to research QuickBooks-certified accountants near you.
Since you're looking to record your gas expenses, I'd like to highlight another feature that might be of use to you: QuickBooks Online's Mileage feature. This can help you easily account for your business-related trips so that you can be prepared to report them as needed. Here's a link that goes over this feature: Set up mileage tracking and vehicles in QuickBooks Online and QuickBooks Self-Employed
I hope this has been helpful! If you have any other questions, feel free to reach out.