You have to learn to walk before you can run. Your not going to run a marathon tomorrow.
Start with walking.
Then after a few weeks, take it up to a swift walk.
Then after a few weeks, quick time. (Run three paces, walk two)
Then after a few weeks, you should be able to start running. Start small, maybe mix some running in with some quick time.
Getting into shape is a journey. It'll take time; but it's worth it.
BTW, breast stroke is an excellent stroke to swim because you don't much forward momentum so you have to use energy.
It will take her forever to get good definition, stamina and lung capacity doing that, high intensity workouts are what help the most when it comes to lowering body fat.