As your kitten grows, so will her claws! And to keep them in trim, she'll scratch. Scratching is a natural way of marking territory and a great way to have a good stretch. As well as the physical marks she'll make, scratching also leaves behind a scent, releasing hormones at the same time. This helps mark her territory and helps her feel at ease with her surroundings.
You mustn't stop your kitten scratching - it's a natural, healthy activity. But obviously you'll want to make sure she doesn't damage your furniture. The best way to avoid this is to provide her with a scratching post, the types covered in a rough surface such as rope or bark seem to be the favourites. Place the post in her favourite room and encourage her to use it by scratching it yourself, mimicking her actions. You could also rub a little catnip on it to make it irresistible.
Kitten's claws grow continuously, so you'll need to trim them every couple of months. Your vet will be happy to do it for you, or he can recommend the right clippers if you decide to do it at home. Just make sure you ask your vet's advice on the safest way to trim.