In your Shopify admin go to Apps → Sellvia → Product List:

Select a collection and click Import:

Note. You can create a new category from the dropdown menu by clicking the Add new collection option:
Once the product is imported, you can find it at the bottom of Products of your Shopify admin:

To have the product in your store, assign your store as an active sales channel for the product. Select the product, click More actions → Add available channels, select your store, and click the Make products available button.
When someone buys a Sellvia product you imported, you will be able to send the order to our US Warehouse.