my basics on the basics, someone might come along and correct me. This would be the same for all Nikons and Canons DSLR, and a lot of point and shoot cameras have these options too.
The "S" setting on the dial (great for starting off, so you don't have to worry about aperture)
This means Shutter Priority. If you set it on S, then all you have to do is adjust the Focus point, shutter speed and ISO. The camera sets the aperture automatically.
The "A" setting on the dial
This is Aperture Priority, as above, all you have to do is adjust the Focus point, aperture dial and ISO and the camera automatically sets the shutter speed.
The "M" full manual settings
For M, you need to set Focus points, shutter speed, aperture, ISO
Focus Points: You move the focus point around the screen with the up/down/left/right controls with your right thumb. When you have it where you want it, you half press the shoot button and it will auto focus on that point only.
Light Meter, for all the M, S and A settings:
Looking at the light meter at the bottom of the viewfinder.
It has a + |||||||||||0|||||||||| - symbols. The aim is to get the light set at zero (middle of the scale). You adjust the shutter speed and aperture to make those changes to the light meter.
Try keep the shutter speed more than 100, try for 200 or higher just to be safe (or you'll need to use a tripod for slow shutter speeds).
I usually try to go a couple of clicks higher on the light meter to blow it out a bit (more light).
ISO: If you find you can't get the light meter to read zero and it's too dark, you might have to increase the ISO.
Aperture and depth of field
The lower the number, the more light, the narrower depth of field. (small area is in focus and the foreground and background is blury)