What is wrong with these pictures

[peety3]

I kept finding the camera at f2.8 but I tried to keep it at f8 or above.

What do you mean here? Either you put the camera into a mode where you control the aperture (M or Av) or you don't (Auto, P, Tv). The only wiggle room there is that P does allow you to override.

I was using one shot focus and rapid fire when I got this image.

Ding ding ding! This can be a big contributor. One-shot focus not only locks focus, it also locks exposure as soon as focus is locked. If you recompose in any way, you'll have both a high potential for out-of-focus shots AND a high potential for incorrect-exposure shots.

I'd highly recommend you switch to AI Servo. I'd also recommend you customize the buttons on your camera to make the AF-ON button actually serve as an AF-OFF button. When you do that, you regain the ability to have focus lock on the rare occasion you want it, but you preserve continuous metering and of course you get continuous focusing. (Others might then say to do back-button focusing, but I'd suggest more time with your camera before you take that leap.) Our cameras stay in AI Servo probably 97% of the time. The only time I put them into One Shot is if there's an external flash on the camera and I want to use the focus assist lamp (it only works in One Shot focus).