Second one depends on where your from, Fashion sense and style largly depend on the social and media influencing the trends.
Try to dress like what other girls in your area wear, but make it unique, dont be a copy of them. Maybe try to look up fashion on google, or in teen mags.
With weight loss, dont try fad diets to much. Try to stick to healthy and foods that are good for you, cut down and replace what "junk" you eat. Try to have smaller portions when you eat and eat more often, it doesnt make sense but it works. Its Believed eating 6 small healthy meals a day is better then 3 or less meals and it also boosts your metabolism making your food digest easier and not storing the fat.
Exercises for weight loss depends on what you want to trim. Try going for a walk around the block and do short burst of jogs, to find the motivation take a friend or listen to an ipod, even take your dog for a walk. If you dont have one maybe put posters up offering to walk dogs for a set amount, earn money while you burn fat! Set goals for yourself, but not hard ones start easy something like walk for 10 mins and get bigger and better goals! this can be your cardio. Stomach crunchs are good for toning a flat belly doing sit up and push ups can increase your muscles.... there are a lot of excercises maybe google some more if you need ideas.
Make sure your having fun, If your not then your more likely to give up faster. With diets make sure you include a treat, this will stop you from doing binge eating bad foods.
Hope i helped, feel free to pm me if you want to chat