i posted about this a long time ago here's the thread..
http://www.yorkietalk.com/forums/sho...ight=ring+bell, about my coco learning to do this in 30 mins. my hubby got one of those collars with the bell on it and took the bell off the collar attached a spring to it and nailed it to the corner of the wall next to the door. it is small and unnoticable and perfect for paws. what he did was he kept saying ring bell coco,pointing at the bell, and putting him next to the bell and showing him how to ring it with his paw, after he would ring it he would give him a treat and open the door even if my hubby was the one holding his paw and ringing the bell, he repeated this until coco realized that if he rang the bell he would get a treat and we will open the door. so after about 30 min he did it on his own, so then my hubby would say ring bell coco and when he did he would only open the door and not give him a treat.the treat was just to get him to learn how to use his paw to ring the bell. now he abuses it ofcourse he rings it even when he doesn't need it and he just wants to go out for the heck of it!

i hope this helps if you have anymore questions feel free to ask, i'm sure your baby will get it.