How can I get my other cats to accept my new kitten?

I recently brought home a new kitty. She's only been here 2-3 days. The first night I had her upstairs where my other 3 cats could see and smell her but couldn't harm her, but my other three cats all hissed at her and ran and hid and they wouldn't eat as long as she was there so I moved her into my basement and now my other 3 are back to normal. Is there anything I can do to help the accept her? Also I can't get her to use a litter box, do you have any tips for that? Please and thank you!

You need to give it time for them to get used to each other then it will be fine

Don't separate them, that's your first mistake. That's normal for adult cats not to like kittens or any new cat for that matter. It takes time be patient. Eventually they won't mind. That always happened with me when ever we brought a kitten or new cat home with other adult cats present. As for the litter box thing you just got to babysit the cat and when ever it looks like its sniffing around and getting ready to go to the bathroom pick it up and move it to the litter box and then encourage it to go to the bathroom. It also may help if there is poop from one of the other cats in the litter box, if the kitten smells it, it should be able to pick up on on the idea. Again all of this takes time and patience. Good luck!

Their still getting used to her,don't worry. To your cats,it would be like your mom bringing a stranger home to live with you,so they have to get used to her. Also,give your other cats some attention too so they won't feel left out or jealous.If you want her to use the littler box,put her in it and let her get used to it. Put in a place not so far from her bed and she will know where to go.