Hello gregfoss1,
In order to do this you can use REST API. The list of REST APIs can be found by the link: http://devdocs.magento.com/guides/v2.0/rest/list.html
First of all, you need to create new cart. The next request will get CART_ID back to new empty cart.
POST /V1/carts/mine
You need to add new product into the created cart. It can be done with the help of :
POST /V1/carts/mine/items
With parameter:
{
"cart_item": {
"quote_id": <CART_ID from previous call>,
"sku": "PRODUCT_SKU",
"qty": 1
}
}
You should also check next requests:
PUT /V1/carts/mine/items/:itemId
POST /V1/guest-carts/:cartId/items
PUT /V1/guest-carts/:cartId/items/:itemId
Regards,
Plumrocket Team