As a beginner, I personally think you did a great job! I especially like the one where the subject is moving his hands.
With that said, here you go. First let's discuss White Balance and how to correct it. What is White Balance? Well, it is a very unique adjustment with digital cameras. In the old days of film, a photographer used different types of film depending on shooting conditions.
Let's keep it real simple (I can get more complex if you need me to). Your camera is going to look at a scene and try to reproduce it as you are seeing it. The problem is your camera, any camera, is just not as smart as your eyes and brain. While people are not perfect, take clothes from a store under their lights and watch the color change when you hit sunlight, we do the job a lot better than cameras.
Now you can get into grey cards for your white balance, but there are some advantages by avoiding this in your beginning, big ones. You want to learn how to take your camera off of automatic or program mode and getting a grey card can be the equivalent to limiting your understanding and creativity as choosing those shooting modes.
Color ranges from cool to warm. Now instead of explaining how or why, I'm just going to jump right into what they are and what we call color temperature.
We use the Kelvin scale, hence the "K" after the temp's number. Lower numbers are cooler, or have more blue, and higher numbers are warmer, or have more orange.
Your pictures are very warm, but that does not mean they are bad. Simple question, do you like them? If so, the color temperature is fine. Are you trying to reproduce a more accurate skin tone, cool it up a bit.
Later you can get an Expo Disc, it just the best product possible, but your not ready for that.
Second, the focus issue. While some will argue manually focusing is always better than auto focus, auto focus is always, again always going to work better providing you are using it right.
Our eyes can not focus contrast as well and not even remotely as fast as today's cameras. But where are you focusing? Chances are you are using the all camera's focus points. Don't do that. Use the one in the center only, you can change this setting in the camera or on the fly.
The center of the camera will focus most accurately and you can control what is in focus, the real advantage. So let's use your pictures. You want perfect focus? Take the center red square you see through the view finder and focus on your subject's eye. Then re-frame for the shot you want.
You probably have the lens that came with the camera, so you are going to be limited on picture quality and focus effects. Don't worry about that, you have a lot more to learn before you'll need to know this. Try opening the Aperture as wide as the lens will go, that is the lowest number, while asking your subject to sit real still. You'll let more light in but blur the background. The faster shutter will allow everything to be black.
Lastly, try coming in real close just getting the face or eyes alone. You don't necessarily need all that black around the subject. Also try tilting the camera to the right or left by 30 degrees or so. Play with it and get creative.
Any future spending should be on better lenses. Any professional photographer will tell you, it's not the light, the camera, or any accessory you start with, it's the lens.
Ask more specific questions if you wish and I will respond. I hope this helps.
-Nick