Please click on the 'Multi-city' button when starting your search. You can then add your dates, destinations and additional flights from there. At the moment, we don't have the price alert option available for multi city searches, however we are working on it and hope to have it soon!
More information about how to search for multiple destinations can be found in this article. This is a new feature on Skyscanner, and we would welcome any feedback to help us keep improving! Please click the contact us button below to send us a message.