Frustrated

I am having problems getting my dog to listen to me on two different things.
The first: at night when everyone is in bed and we are still up, she can't go upstairs because she will wake everyone up. She doesn't listen to me when I tell her to stay downstairs. I have tried smacking her behind when she attempts to go up, and I have tried putting her in her cage when she doesn't listen.
The second: She has learned how to open the sliding screen door. We don't want her to do it because it lets bugs in. She won't listen when we tell her to stop.

Other than these issues she listens perfectly to everything we tell her. She is a lab/retriever mix and about 1 year 3 months old. What can we do to get her to listen?