Select customer by email HELP PLEASE!

Select customer by email HELP PLEASE!

Hello. I am new to Zoho Creator and the Deluge language and I really need your help. I installed the Order Management app. The New Order form, a customer can only select their name using a lookup field which shows all customers in the dropdown. Since our customers will be ordering online, this will not work because we don't want to show all of our customers in the dropdown. We want the customer to enter their email address and have the app to search for the customer in the Customer database using the email address. If found, the name will populate, if not found, the customer will be directed to the new customer form to enter their information then sent back to the Order form to complete the order. I have tried many things but it still doesn't work. I read all the eBooks and watched all the tutorials, webinars and videos and still can't get it to work. It is hard because all the training material use the old version of Creator so some things are hard to relate. I was a software developer in my previous career so I understand the basic concept. Can someone please help me?