Hi there Donna Weaver,
It's important that all your transactions are entered correctly for your books to be well balanced. QuickBooks Online is a great tool able to help you keep track of sales and expenses so you can see the profit of your business. I can point you in the right direction for information about apps.
In order to view the apps available to connect to QuickBooks Online, you can go to the Apps section, then type in a keyword to search for tasks and features that you'd like this app to accomplish, and you can view information posted by the app developer as well as reviews by users to help you make your decision.
If you have any other questions about QuickBooks Online, feel free to reach out here.