In order to ship a sales order dispatch it first needs to be fully picked, you can tell when stock has been fully allocated against a dispatch when you see a green tick appear against the BOM icon 🧩.
There are two ways you can ship a dispatch, this can be done either from the Sales Order screen or from the Workflow.
If shipping form the Sales Order screen click on the workflow dropdown next to the BOM icon and select "Shipped", optionally select a courier and enter a tracking number and click "Yes" to complete this dispatch. In turn if setup this will email the customer a copy of the invoice and tracking information and transfer the invoice into Xero.