ventilation

I'm new here and have tried to take care of my pony as best as i could as the previous owners did not (been in the family for many years and was treated as just a car). I'm not sure if it's the tansmission, every time I put the shifter into D I get very little acceleration and the rpm's go up...

My A/C gives perfectly ice cold air at the wind shield outlets. When I switch over to floor or instrument outlet, nothing happens. Any with this experience? Any with good idea what it can be? Where behind is the part located that direct the air to desired outlet?