Step 1: Open a Sales Form
Open any sales form, such as an Invoice (Ctrl +i), or an Estimate (from the Customers menu, choose Create an Estimate).

Step 2: Enter a Customer Name
Enter the name of a new customer in the Customer: Job field. Just enter the customer name, not a job name. Click in another field of the form, or press the Tab key to move to the next field. The Customer: Job Not Found window will appear.

Step 3: Add Customer Name to Your Customer List
Click the Quick Add button and your Customer Name will be added to the Customer List. You will be advanced to the next field on the sales form.

Step 4: Add a Job for this Customer
Now that you've set up this customer, you can add a job too. Return to the Customer: Job field by clicking in the field. Right after your new customer name, enter a colon (:), and a space, followed by the name of your job. Click in another field on the form or press Tab to advance to another field.

Step 5: Quick-Add the Job
When the Customer: Job Not Found window appears, click Quick Add again. This will add the job to the master customer list. No information other than the name of the customer and job are entered in your QuickBooks records at this time. To enter information such as the customer address, phone number, credit limit, and so on, take a look at the tutorial on Adding a New Customer.