Remember that the bladder of a nine week old cat is veeeeery small. And, kittens have so much fun exploring and playing that they realize way too late that their tiny bladders are too full. Even if they want to make it to the litter box, they just can't hold it and they have an accident.
So, carry the kitten to the litter box every other hour, but don't force it to get in. Just carry it in and put it down near the box so it will remember to go if it needs to (and it may not need to).
When you're not home, confine the kitten to the room with the litter box as the others suggested.
Once the kitten is a little older, you'll find that the problem will go away.
Remember to clean all of the old accidents with an enzymatic cleanser so she won't think of the old dirty spots as appropriate places to pee.