POST api/AddToCart

{
  "order": [
    {
      "qty": 1,
      "integration_product_id": "sample string 2",
      "product_price": 3.0,
      "design_price": 4.0,
      "unit_price": 5.0,
      "integration_associate_id": "sample string 6",
      "integration_product_name": "sample string 7",
      "additional_options": {
        "product_design": "sample string 1",
        "printing_method": "sample string 2",
        "printing_surcharge": 3.0,
        "custom_options": "sample string 4"
      },
      "designer_url": "sample string 8",
      "image_url": "sample string 9",
      "item": "sample string 10"
    },
    {
      "qty": 1,
      "integration_product_id": "sample string 2",
      "product_price": 3.0,
      "design_price": 4.0,
      "unit_price": 5.0,
      "integration_associate_id": "sample string 6",
      "integration_product_name": "sample string 7",
      "additional_options": {
        "product_design": "sample string 1",
        "printing_method": "sample string 2",
        "printing_surcharge": 3.0,
        "custom_options": "sample string 4"
      },
      "designer_url": "sample string 8",
      "image_url": "sample string 9",
      "item": "sample string 10"
    }
  ],
  "sessionToken": "sample string 1",
  "entityId": "sample string 2",
  "firstname": "sample string 3"
}

<OrderDetails xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/MagentoAPI.Models">
  <entityId>sample string 2</entityId>
  <firstname>sample string 3</firstname>
  <order>
    <Cart>
      <additional_options>
        <custom_options>sample string 4</custom_options>
        <printing_method>sample string 2</printing_method>
        <printing_surcharge>3</printing_surcharge>
        <product_design>sample string 1</product_design>
      </additional_options>
      <design_price>4</design_price>
      <designer_url>sample string 8</designer_url>
      <image_url>sample string 9</image_url>
      <integration_associate_id>sample string 6</integration_associate_id>
      <integration_product_id>sample string 2</integration_product_id>
      <integration_product_name>sample string 7</integration_product_name>
      <item>sample string 10</item>
      <product_price>3</product_price>
      <qty>1</qty>
      <unit_price>5</unit_price>
    </Cart>
    <Cart>
      <additional_options>
        <custom_options>sample string 4</custom_options>
        <printing_method>sample string 2</printing_method>
        <printing_surcharge>3</printing_surcharge>
        <product_design>sample string 1</product_design>
      </additional_options>
      <design_price>4</design_price>
      <designer_url>sample string 8</designer_url>
      <image_url>sample string 9</image_url>
      <integration_associate_id>sample string 6</integration_associate_id>
      <integration_product_id>sample string 2</integration_product_id>
      <integration_product_name>sample string 7</integration_product_name>
      <item>sample string 10</item>
      <product_price>3</product_price>
      <qty>1</qty>
      <unit_price>5</unit_price>
    </Cart>
  </order>
  <sessionToken>sample string 1</sessionToken>
</OrderDetails>