New Grower Hii im new to growing just need explanation oneverything especially ec/ppm and any other for of mea

[desert_high]

I am new to this i have a the whole setup ready but my friends keeps on bailing on me when i need him.. the seedlings are out 3 auto-mazar in my aero garden im goona switch them to the pots in the tent using 2 400 watt hps lights not sure wat nutes to use and how much to use and how much ec/pm etc.. how often do i water and how often do i feed? room temp