How can I start running?

I am 13, a girl, five feet and three inches tall, and weigh 120 pounds. I am not classified as overweight but i just don’t feel good in my body and want to lose some weight and also just get in better shape. Basketball season is around January and I also want to get ready for that.
I just hate exercise but I have tried running this past week and actually like it. The problem is, I’m terrible at it. I run in my neighborhood, which is relatively hilly and uneven. I alternate between running and walking for about fifteen to thirty minutes, but the length I run is not very long and I’m wondering how I can work up to running longer without stopping, possibly as long as a mile.
My legs are very sore right now from running the past two days. I want to know if I can really lose weight by running and how much. Also how can I work up to running a mile and how many times a week should I run? I am a complete beginner and any advice is appreciated.