Example:

curl --request PATCH \
  --url https://api.hips.com/v2/orders/UVWofp7AjHiRKNLjhUjMnhc3 \
  --header 'Accept: application/json' \
  --header 'Authorization: private_9xxJrsc1u2TF6cPCm6JzG2ry' \
  --header 'Content-Type: application/json' \
  --data '{  
   "order_id": "123",
   "purchase_currency": "USD",
   "user_session_id": "3246568465743",
   "user_identifier": "SmartShopper17",
   "cart": {  
      "items": [  
         {  
            "type": "physical",
            "sku": "3123123",
            "name": "Hips cup",
            "quantity": 1,
            "unit_price": 1000,
            "discount_rate":0,
            "vat_amount": 250
         },
         {  
            "type": "shipping_fee",
            "sku": "1",
            "name": "UPS Express",
            "quantity": 1,
            "unit_price": 1000,
            "discount_rate":0,
            "vat_amount": 250
         }
      ]
   },
   "require_shipping": true,
   "express_shipping": true,
   "hooks": {
    "user_return_url_on_success": "https://mystore.com/thank_you",
    "user_return_url_on_fail": "https://mystore.com/sorry",
    "terms_url": "https://mystore.com/terms",
    "webhook_url": "https://api.mystore.com/confirmations"
   }
}'