I'll help you add entries into your books, chris Tan.
If you're referring to customizing your transactions by adding some fields, here's how to do that:
You can also add and customize more a sales transaction. Check out these articles for the detailed steps on how to do so:
On the other hand, if you're referring to creating entries, you can click the +New button from the left menu. If you're referring to creating journal entries, you can use this reference: Create a journal entry in QuickBooks Online.
Our Help articles page is also available if you need more help with creating entries.
Please don't hesitate to get back to me if there's anything else that you need help with. You take care!