Hello there, user1234,

You can create an invoice by clicking the Plus icon. Let me guide you how.

1. Go to the Plus icon, then choose Invoice under Customers.
2. Select the name of the Customer from the drop-down list.
3. Choose the Terms for the invoice from the drop-down list. 
4. Check the Invoice date and the Due date. 
5. In the Product/Service column,select the item or service.
6. Enter item's Description, Amount, Qty, Rate, and VAT information. 
7. Click either Save, Save and new, Save and close, Save and send or Save and Share link once done.

You can refer to the screenshots below, or check out this article for the detailed steps: How to Create an Invoice.

That'll get you going, user1234. Please let me know if you have other concerns about creating transactions in QuickBooks. I'm just around to help.