Learning to improvise at the piano is not difficult, though it might take a small mind shift on your part. Consider the following. Until the mid 19th c. it was customary for classical musicians to improvise on stage. Bach, Beethoven, and Mozart were all know for their improvising prowess. You can find more inf. and links here:
Musicians wrote books on how to improvise. Click on this for more.
Have fun. More to come.
You've got to learn your instrument. Then, you practice, practice, practice. And then, when you finally get up there on the bandstand, forget all that and just wail.
I'm a professional pianist and music educator in West Toronto Ontario. I'm also a devoted student and teacher of the drums.