As you build the network and change details like duration, calendar, etc., you can update the schedule by clicking the blue Schedule button on the top right.
To schedule the project your will. need Start Milestone, connected to the first activity in the sequence and provide a start date. Please see this article to learn more about Milestones
The schedule button has two states - schedule is updated and stale.
Each time you run the schedule, you will be able to see a summary change from the previous schedule run.
If there are any errors or warnings in the network, you can see them here. We highlight the following warnings: