I particularly like using the Litchi website's Mission Hub on my PC for creating WayPoint mission flights. You can also create/edit WayPoint missions with the Litchi app on your iOS, tablet or smartphone device. For me, its just so much easier to do this on a large screen like a PC has. If you are logged in to the Litchi website and Litchi app on your iOS or Android device the WayPoint missions will be automatically synchronized (uploaded or updated).
Its also worth while to read Litchi's User Guide on their website here: https://flylitchi.com/