For thousands of years we have been creating music, from the first rhythm on a log to the classical ensembles we have today.
Two very easy instruments that I am familiar with is the hand drum and the piano. Both of these instruments are easy to play freeform; One can get a good sound anyway one can touch it.
The first problem people have with playing instruments is that they think that they can't and therefore don't even try. Or, they could just be scared of other peoples criticism.
Well, anyone can play an instrument, particularly the piano or drums.
One can drum on anything whether a bucket, a table, or a real hand drum. This means you can do it just about anywhere. One should only use the hands and not sticks because you get twice as many sounds from the the same object.
Whether using a Tabla, Congo, Djembe, or a bucket you will always have at least three sounds: the deep base found in the center, the high on the edge and the occasional clap.
You can alter the highs and lows.
Tap center=base sound with resonance
Tap center without removing hand=Base sound with no resonance
Tap rim=high sound with resonance
Tap rim without removing hand=high sound with little resonance
Put elbow on the center while tapping rim with other hand=pitch bending (like the talking drum)
Uses individual fingers for speed
By altering the speed (rate), the volume, and the different sounds anyone can get some groovy rhythms.
The piano is bit more difficult than the drum. When beginning freefrom piano you should not use any more than one or two keys at a time.
Find what sounds good together by picking two keys and play them together and also in a sequence.
After you find a variety of two key combinations (like octaves, or A+C, C+E) combine them (like A+C+E).
With this combination play one with the left hand and the same an octave higher with the right hand.
Then, think of these keys you have found like a drum. Make a rhythm out of only a few keys.
After you get bored from that rhythm add some other keys into the ensemble and see if they sound good.
Through trial and error you piano playing abilities will evolve.
Remember rhythm is very important. The more intricate the rhythm, the better the music.
Playing music is like meditation. It can clear the mind and is invigorating to the mind. It is a way of expressing yourself without words. Playing the music is much like telling a story. In fact I read in Scientific American Mind that when freeform musicians play the area in the brain that tells stories fires.