no worries! what are you having trouble with specifically? the way the expressions work is that you grab certain points of the face (indicated by the small white circles) and drag them into place. then you grab a pin from the pincushion and place it there before it moves back (it should stay for a couple of seconds, so there should be enough time to pin).
there are a bunch of different expressions that can be made as indicated on the right side of the screen! once you make a new face, the detected expression should update with what that is.
hope that helps!