for my fangame how do you make a weapon charge

what code do you use to shoot and and if you hold it charges a stronger bullet :confused:
and also how do you make the little spark things when you charge! :confused:

Official Fangame Help Topic

It looks like you need:
A.) Some variables and some variable logic (bool expression checks)
B.) A particle system or a small animation of some particles

Less complicated than it sounds, but ask about it in the fangame help topic.