Send JSON Array on Body -> form-data

Hello there,

I want to post data on the form-data in Body to the that api which structure in below but i cannot send truly.

Can you help me to the send this array?

"Format": [string],
    "Order": {
    "OrderShipment" {
    "OrderInvoiceAddress": {
        "OrderLine": {

This is structure.
I tried this key on data but didn’t work. =>