5 kittens (6wks old) & 1 litter box?

This weekend I introduced them to a litter box, but only one or two will use it, the rest are using the floor in the corner of the bathroom (where I have inclosed them with the litter box). What do I need to do?? Are they old enough to give away? If my local human society won't take them and there is no one I know who wants a kitten, is there somewhere else i can take them? I live in Columbus, GA... I am getting my cat fixed PRONTO!!! Also, I bought a bag of dry cat food and my cat didn't like it, is there somewhere that might take it???