Lisa,
Congrats on the new camera and Welcome to the forum.
As stated the kit lens isn't going to out zoom your point and shoot camera. For sports a longer zoom is needed. Just a few questions?
What is your budget for the lens? What kind of sports do they play, is it all inside, outdoors or both? Would it also consist of outdoor at night?
Take a look around and hope you stay, this is a great place for help and information. Be sure to check out the "Sports" forum for tips and help that you might run into.
James