Just mostly focus on chest exercises. I dunno if you going for power lifting for size or just toning. If you going for size, go power lifting. Meaning go low rep, high weight, 8-10 reps. If you just going for a tone then go high rep, low weight, 10, 12-15 reps.
Two good exercises you can do is flies and dips. Flies you lay across a bench, similar to a bench press position and you hold up two dumbells straight up(you may know this). You slowly extend your arms out to your sides(similar as if you were hugging someone) then back up. After about 5-6 reps, you then take the dumbells and rotate them to a dumbell press(very similar to the bench press, except using dumbells) and do about 5-6 more reps of them, no break, for a total of 10-12 reps. If you power lifting then go for about 8-10 reps. Repeat for about two more sets. You could do them individually as well if you choose too. Like dumbell flies only or dumbell press only for 8-10 or 10-12 reps. I choose to mix the two for it helps give you a better "burn" and it works multiple muscle groups in your chest area. This was how I was taught.
Here are examples for each:
http://www.exrx.net/WeightExercises/PectoralSternal/DBFly.html
http://www.exrx.net/WeightExercises/PectoralSternal/DBBenchPress.html
Dips is another good thing to work pecks on. If you are overweight though this could be tough for you. You could do elevated dips which are much easier because you prop your legs up which is less weight that your lifting. But I believe however, they focus more on triceps. For dips you'll need two parellel bars to hold yourself on. You hoist yourself up with your elbows locked and legs dangling in the air. You then proceed to lower yourself down and push yourself back up again and just keep repeating. Very similar motion as pushups except your body is vertical rather than horizontal.
Something like this:
http://www.building-muscle101.com/parallel-bar-dip-exercise.html
Not sure how accurate these sites are as far as information goes. I'm just using them for illustration. What I'm telling is what I was taught.
Theres also bench press, and inclined bench press which is more upper chest/shoulders. Push ups is good too. Theres a machine excerise where you sit down with your legs straight out and you have two handles attached to the machine that you pull towards you up to your stomach and you extend them back out. I can't remember the name of this exercise so I can't really show an example. This is a good way to build peck muscles as well. If you want that "V" shape upper body, focus on laterial exercises like lat pull downs. You'll probably need a machine for those. You grab a bar hanging over your head while sitting down and you pull the bar down to around your chest area and back up again. Very similar to pull ups except your sitting down. Those build your muscles around your side and gives you that "V" shape.
If your new to these exercises, just start off with light weight so you can get used to the motion and doing them correctly. Then up the weight. That way you don't hurt yourself with an accident or pull something. Don't rush things. Your muscles will build over time. Its a very slow process. Just stick with it. Remember not to build your muscles two days in a row. They need time to heal so they can grow. Sit ups is the only thing I can think of that you can get away with doing everyday. They are a special type of muscle that doesn't break down like our limb muscles do. Theres a name for this but I can't remember it but it allows that muscle to be worked on daily because of a certain type of resistence it has.
Good luck with acheving those pecks lol
. I hope I was somewhat helpful.
lol
