Where is the "Start Shipment" option?

Shipments can be created and sent out only by the Facility Managers, so if you're only seeing incoming and outgoing shipments, you'll need to switch roles. Organisation Managers can only see an aggregated view of all shipments across all facilities within the organisation, but are not intended to handle day-to-day activities.

To switch roles, just click on the dropdown at the top right of the page. The line with only the organisation name corresponds to the Organisation Manager role, and the line(s) where you see the organisation name paired with a facility name are for the Facility Manager. Select the new role, head to the SHIPMENT tab, and you'll be able to start shipping.