Here are some exercises to help you become more familiar with 16th note groupings. Count out loud as you play each one and tap your foot to help you keep time. It would also be useful to practice them with a metronome or drum machine. If you are serious about music you should be using a metronome for everything you practice. A musician with good control of rhythm and timing is always popular with other musicians.
Once you are comfortable with these basic 16th note groupings, it is easy to create great sounding keyboard parts using simple patterns. Here are some examples.
Notice the F note in the chord under the C7 symbol in this example. This is called a suspension, which means substituting the 4th degree for the 3rd. Suspended chords are discussed in lesson 39.
The following examples demonstrate parts which feature much interplay between both hands. Practice them slowly at first with a metronome and gradually increase the tempo until you can play them comfortably at a fast speed.
This one is a variation on the previous example.
Here is a slightly more complex line based around a C minor arpeggio.
In this one the right hand plays full chords but both hands are still working together.
This one takes the same type of idea even further.
This Gospel style 12 Bar Blues is based on an underlying 16th note rhythm. Take it slowly to begin with, and practice each hand separately with a metronome if you need to.