Good thing you are aware of your health and striving to start exercising! Here's the breakdown:
Muscle explosiveness/strength/endurance:
Just do body weight exercises since general muscle tone is the aim for beginners
Pushups for upper body
Bicycle crunches for midsection
Squats for lower body
Body composition/cardio endurance-Go running with your running shoes, this is more challenging and physically demanding than the treadmill anyhow
Flexibility-Stretch
So 3 things you should start doing if you want well-rounded fitness-Running, body weight exercises, stretching. You don't need to use your 10lb weights, pushups is much better, especially if you're a girl. Jumping rope is also great for cardio, but you might need to go buy the rope.