There is clearly mentioned that there are no resources in this class yet on the Udemy course. For me it is not a problem because creating or choosing the graphics ourself let us make our own creative results from the same course.
Maybe we have to draw our own graphics, which is a very good exercise. As a second option you can buy the graphics here also on the Scirra website.
I remember from earlier tutorials, there are flappy bird graphics in the media files, coming with Construct 2.
If you make the graphics yourself, you will get a better idea.
I like this course very much so I can recommend it to others too who are serious in learning Construct 3.
By the way, our daughter Karabo did put the smileys on this reply. hello from Karabo