Adding things to the "My List" feature is a great way to keep track of everything you want to watch on Crave!
If you open the Crave application there should be a + option next to the show name when you select a show. This won't occur though if you select an episode. To my knowledge this functionality should be available within each app across all platforms however I haven't had the opportunity to test it myself.
Let us know if this isn't showing up for you! A photo of what you're seeing could also go a long way to assisting :).