If I am reading your post right, you are 5'4 and 110 pounds which means you are at the low end of the healthy weight range for your height so I would say if you increase your exercise you should be careful, and be sure to increase your calorie amount so you will be able to increase your muscle mass and not end up losing weight (and muscle.)
Most likely what you want to do to tone up is do some weight training, not a large amount of cardio. Cardio will burn calories and if you burn too many calories you will lose muscle mass,which is also why you should make sure you are getting enough calories, and also enough protein. So I would get some weights if you don't already have some, and look up weight training exercises. One site that you can find videos for how to do these exercises is Sparkpeople.com.