How to build chest muscles...?

do a variety of exercises, employing different angles and different rep ranges to find which exercise works best for you. Generally speaking I find flyes and cable cross-overs stress that area moreso than other exercises, but to be quite honest your chest has to grow as a whole - you can't target one particular region.

if you mean your pecs then pushups and bench pressing are great exercises.

homie if ur bonny u aint gonna get pecks in no time soon! u need mass.... bench all you want! wont do any good. u'll get stronger and leaner! not mass though.... u need to get mass or weight first then build muscle. how tall r u ? weight? age? all key factors! how much weight are u capable of doing? I preffer doing decline benching w/ dumbells... much better to lift ur pecks n make them noticable... w/b

I asked a similar question sometime back. This is one resource I found useful.

First off, you're a lot better off building all your muscles than just one specific area, because they all work together and help build each other (through increased testosterone release). Find a good weight lifting routine. Make sure that it includes bench press, pull-ups, deadlifts, and squats. The training forums at www.sherdog.net have some good lifting routines in the stickied threads. I get most of my lifting info and advice there. If you get a good workout routine goin', combined with a good diet, your body will shape itself how it needs to be. However, just an FYI, I'm 5'9", 198lbs. I can bench 255 for a set (haven't tried to max lately. dont really care). My chest muscles are pretty well developed, but I can still feel my sternum (breast bone). That's somethin' that will always be with you. Look at any bodybuilder (gag) or professional athlete. They have a valley between their pecs where the muscles conect to the breastbone. There's no muscles in the center of your chest to get bigger, if that's what you're askin'.