If as your profile suggests, you are an EU citizen, the procedure is no different than going to the US to visit Disneyland. You simply need to fill out a Visa Waiver form on the airplane. Remember though to state in the section "Reason for visit" to say holiday and NOT training otherwise you may have some problems with the immigration guys. You will not be making a misdeclaration by stating this. If you intend long term training, this is altogether different and you would need a J1 Visa which you will not need simply for PPL training. Good luck!