How do I get my pre-order forms back from my customer?

I custom made an order form but i have no clue how they fill it out and send it back to me

If I understood you correctly you are asking how will you receive data that your users enter inside of your form. 

First you will need to provide your users link of your form. You can send them link of your form via email. You can also sent them link of your form from our interface. 

How to send a form via email

If you have website you can embed your form there and provide your users URL of your website. 

Adding a form to a web page

Once your users open your form, they will need to fill it and submit it.

I have inspected your form and your form does not have submit button. Without submit button your users will not be able to submit your form and you will not be able to receive submitted data. You need to add submit button to your form. 

Once your users submit the form, email Notification will be sent to recipient email address that is set inside of your email Notification. By default it is the email address of your JotForm account. 

Explanation of Email Notification and Autoresponder Settings

Submitted data will be also sent to our servers and you will be able to view them on submission page of your form.

How to View Form Submissions

Hope this will help. Let us know if you need further assistance.