Help for total noob

OK. I am not a gamer. Last game other than Bejeweled 3 I played was Quake on a network. I bought a new video card and it came with a download code to the Witcher 3. I got myself a gamepad Logitech F310 and have it set in X mode. I do have a joystick too but only use that for Quake. So here is my problem. I have loaded The Witcher 3 and I am trying out the demo mode tutorial. I have wandered around all over the place but I have no idea what to do. The game is telling me to go to a lower level but I cannot for the life of me figure out how? I found a key on a book and now it tells me I can open doors by pressing A but I am not finding any doors beside the one which is open and has the mountain view. Remember I am new to this, I am staggering around like a drunken moron and if I can't figure this out I guess I'll have to quit it. Anyone got any tips for an old fellow?

Is this after talking to the woman with no clothes on? If I remember rightly if you look out of the window with the view the door is just to the right.

Yes she soon got dressed.......There is a door that goes outside to a view of the mountains but saw nothing as a way to proceeded that direction. OK I'll try that.

AstaLaVista have not been able to find anything so basic yet. Lots of tips but I ain't got out of the room yet.

There's a big wooden door that's closed, it doesn't face out of the room as it leads to an internal staircase.