Order forms for partial payments and services with preview form with payment processing

As I can make an ordering system for Digital Services, but with options for partial payment, ie the customer to pay first 50% of the price of the service and then when the soilicitado work is completed must pay the remaining 50% of Total wreck Service

How can a Form Preview, or customers can by cun code obtained in the initial order, enter this code in the Form Preview and display content that you took the form or in its effect by database, what I want is that in this form can view images, audio, video, websites, etc. Anyway, embedded or loaded, but that the customer can see a preview of the work already done and if you like tner options for the remaining payment service, or half 50%

If I can help to know how I can do this I am very grateful

I am not quite sure if I understood the workflow correctly.

Order or payments in the forms are processed directly in the 3rd party payment gateway. Once submission is done, the transaction is completed, so there's no partial payment. Unless you want it to be setup as a subscription, subscription can charge your users on a scheduled basis, you can setup a different initial payment from the succeeding ones. Here's a guide on how to setup a payment form: https://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form 

Another way to ask for the partial payment is to let your users to fill out the form again and hit the submit button.

In my case, this is how I will set it up:

1. First, I'll create two forms, Form 1 is for the initial payment, Form 2 is for the half/partial/remaining balance.

2. User needs to fill out Form 1, you then provide service to them.

3. When the service is finally completed, you then just need to provide them Form 2 and fill it out.

Another way is to integrate your forms to your system. From the looks of it, you want something more complex. You might need to hire a developer for this. If you want to prepopulate the form based on an existing record using a code, then you might need to create your own system as this may not work with JotForm only. Here's how I will do it:

1. First, you need to have your own database, something like MySQL that is host in your own web server. 

2. After that, you can directly send the submission data to your database using POST method. Here's a guide on how to do that: https://www.jotform.com/help/126-How-to-send-Submissions-to-Your-MySQL-Database-Using-PHP 

3. Now, you need to embed your form's full source code to your website page, you then can create a custom script to where you can associate a code and give that to your user, when he/she enters the code, your custom script will automatically prepopulate the form fields based on the existing data in your MySQL database.

I hope that gives you an idea on how to proceed.