To get a big chest fast, you need to do bench press and push up work outs. There are three ways to do bench press work outs. There is the inclined, the declined and flat bench-press. Here is a link to give you more guidelines http://www.wikihow.com/Get-Bigger-Chest-Muscles-(Pecs).
Try different type of push up's such as close arm; make a triangle with your hands under your chest and push up, or even a 90 degree push up; having your hands at your sides with elbows at 90 to give you more results by working different muscle groups and adding a challenge