Go to the Shopify app store and install the "Codefort WMS" Shopify app.
You'll be asked to provide your subdomain if you're an existing customer.
If not, you can create a new account using the "New customer" form.
Your subdomain is the one you provided when you created your account and can be found in the URL when you're logged into Codefort WMS.
Your Shopify store should now be connected and registered as a sale channel in Codefort WMS.
Go to your Shopify store and update your products to use Codefort WMS as your fulfillment service. You can have some product to fulfill using Codefort WMS, but most users will have all their products set to Codefort WMS.
Create an order with any of the products set to use Codefort WMS as its fulfillment service.
You can now "Request fulfillment". This will create a shipment in Codefort WMS and your warehouse knows that you want to fulfill this order.
Tip: It's typically not practical to request fulfillments manually for each order.
On your Shopify store, you can go to "Settings -> Checkout -> Order processing".
Here you can enable "Automatically fulfill the order‘s line items", this will request fulfillment as soon as an order is created and your orders will therefore be created real-time in Codefort WMS.