If it was a recent order, click on 'View Report' in the 'Last 7 days' row of your 'Recent Orders' section.
If you would like to do a more customized search, click on the 'Order Reports' link under the 'Reports' heading (highlighted below).
Click on the number in the 'Order ID' column to view the order details.
In the 'Order Details' tab, scroll down to 'Order Status.' Change the status from 'Ordered' to 'Shipped,' then click the 'Update' button.
After you change the status to 'Shipped,' click on the 'Ship Order' tab to add the shipment date, tracking details, and send an email notification to the customer. When you are finished adding the details, click 'Add Shipment.'