How to show 2 classes implementing an interface?

[Yash]

I drew 2 classes. I also dropped a lollipop-style interface object. I defined
2 functions in the interface. Then I dropped the interface on one class. The
functions automatically appeared in the class.

But when I drop the interface on the second class, it disappears from the
first class.

How do I show 2 classes both implementing a common interface using the
lollipop-style nottaion?

Thanks,
Yash