Are you even focusing? Make sure you half-click the button before shooting, so the focus comes out nice and crisp. And if you use a small number for your aperture it will nicely blur the background.
Some of this stuff looks overexposed, out of focus, a tad noisy, etc.
Just keep practicing and make sure your focusing on your subject, and try to avoid motion blur also. I'm still noobish myself but I learned everything I know just by tampering around and using the help of this website.
You should also tamper around with photoshop, because photoshop can make a world of difference in your photos.