Learn the basics of depth of field (dof)
1. Effect of aperture on dof.
2. Effect of focal length on dof.
3. Effect of distance from subject on dof.
It's easy with digital to just take a lot of photos of the same scene and just change the aperture for each one. Then compare them on screen to understand how to get what you want to be in focus or blurred by changing the above factors.
You will soon learn what aperture to select for any given lens/distance to get the effect you want.
Learn the basics of shutter speed. ie what speed you need to deliberately freeze or blur different motion.
Again, get someone to jump around and another of a tap running and take pictures at different speeds and compare them on screen to see what different shutter speeds do.
Then understand the relationship between aperture and shutter speed in getting the correct exposure.
This will give you the basics to understand the building blocks of photography. The joy of digital is that it is cheap and easy to experiment and takes little time too.