New Camera

So I have a new camera, and I went out and took a few shots with my best friend(Ms.Lin). My pictures are coming out very sharp on my camera but when I pull them up on my computer, I do see some graininess. I shot at an ISO of 6400 which is really against the rules of photography. I was so pumped about my camera I couldnt even wait until we got out of the car. I take about 140 pictures or so but in the end only about 70 pictures caught my attention. Most of the pictures here show some of my vision and emotion but still at a bump in trying to convey what I am actually seeing overall. so tell me what you think....NewPics