Usin buttons
That is quite a broad idea. There are hundreds of ways to do it. If you want to make a button launch a missile, one thing you could do is make a button actor, add a collision box, and when your character presses ‘E’ while inside the collision box, the button casts to the missile and launches it. There are many more ways however. If you can describe the way you would like to do it, I could help you achieve it 