First of all, make sure that there some new orders on your main screen in the manager app that waiting to deliver.
If you don't see any available couriers use one (or all) the next articles:
Click on one or more of the deliveries, it will open list for courier selection and their status:
Choose the couriers and you will see the route planning screen:
Here you have some options:
The Couple button - will let the courier option to decline the order.
The Optimize button - will calculate and organize the optimal route for the courier.
The Calculate button - will calculate the ETA's and show it to you before attaching the
You can see the course that you planning:
Then click on:
Finally - click on "Couple".
A short video of the process: