Attaching pen to rectangle

I have my pen tool. I then have drawed my new surface with it but then I want to attach the last point to the rectangle itself. How does I do that?

Rectange…what rectangle are you talking about, a movie clip?

It has the shape of a rectangle. I drawed it with the rectangle tool but when I try to attach I simple select the rectangle, but I want to attach a few lines to a corner of that rectangle.