It can be done, but the voltage output of each piezo will be in the millivolt range, in a short spike. So for example if you connect each piezo to a single high-efficiency LED, you can indeed get the LED to flash with each beat of the drum. But you would not be getting enough output from the piezos to power anything more bright or complex, and the voltage spikes would not be sustained enough to provide a "worthwhile" charge to a battery.
The principles really are "electronics 101", so googling an online introductory electronics tutorial will get you what you need to know. And I'm not saying "do a search" as some snooty thing, but because the basic info you need really is available that way.
