Well Im 15 and want nice abs good arms and a flat chest.LOL who dont but if u no any kind of pattern I can do to help me look better.I do alot of sit ups ,bench press,and just lifting arm weights.What else should I do and shouold I do alot of reps. or do them till i get tired.Also how long will it take to see some resluts?

you shouldn't neglect your other body parts. By only working chest, arms, and abs, you will eventually start to look unproportional, which isn't a good thing. My reccomendation would be to start of with a simple routine such as:

Monday - chest/triceps/delts(shoulders)
wednesday - back/biceps
friday - legs

you can work out your abs on your off days, or put them at the end of your routine

OR

Monday - chest/triceps
tuesday - back/biceps
thursday - legs
friday - shoulders(traps/delts)

when working on your abs, DO NOT follow the myth that 100's of crunches each night will get you a 6-pack.no matter how many crunches you do, or how developed your abs are, the will not show if you have a layer of bodyfat over them. The answer to this is a proper diet, cardio, and a proper training regimen.

your abs are just like any other muscle, and should be worked the same. try to keep the total reps between 8-12. For abs, try doing:
-weighted crunches(on a swiss ball, or with a plate/dumbbell behind your head or on your chest)
-wieghted leg lifts(start with no weight until you can do at least 10 reps. then start to add weight SLOWLY as your strength increases)
-side crunches or trunk twists

try to incorporate the three main lifts into your program (bench press, squat, and deadlift) I would reccomend getting someone who knows what they are doing to teach you proper form on each of these lifts.

each body part only needs to be worked once a week. This may not seem like much, but remember that your muscles do need time to recover. Your muscles grow while you sleep, not in the gym.

one last thing, you do not need to work abs every day. As i mentioned before, your abs are just another muscle group, and should be worked accordingly. working them once a week will yield great results( providing you are using added weight). If you feel that it is necessary, you can add an extra ab session each week

i know this is kind of lengthy, but if you have any other questions, feel free to ask.

another thing, try to keep the number of reps you do between 8-12. choose a weight that you can only do for this many reps while keeping good form. every week, you should try to either increase the number of reps you do, or increase the weight. I will put emphasis on good form because it is essential when trying to gain size/strength. improper form can lead to injury, or very little stimulation to the muscle.

eg. DO NOT swing the weight when doing bicep curls. keep your arm stationary at your side, allowing your bicep to do all the work

eg. 2. when doing bench press, make sure the bar touches your chest. also, DO NOT let the bar bounce of your chest, only touch lightly.