Very carefully.
Let me explain in terms you can understand.
Power is the amount of splashing a bucket of water makes as it hits the floor, this is measured in watts
Voltage is the height of the bucket when it's released, measured in volts
Current is the amount of buckets per minute that you drop on the floor, measured in amperes
(Edited 35 seconds later.)
OK, let's say that electrons are like fists. Volts is the energy per fist. Amps is the fists per second. Watts is what you get when you multiply volts and amps, getting you energy per second.
nobody really knows....