No need to apologize. I may have came on a bit too strong.
This is the filling and leak testing procedure.
I unplugged all the power cables from the hardware (gpu, mobo, ssd's) but not from the pump and radiator fans. The 24-pin from the psu has a (white) loop connector otherwise the power supply won't turn on. The blue/green wire is from the pump (PWM) and goes into the mobo (it looks like it's attached to said white connector but it isn't).
I have a plastic bottle in one hand and the on/off switch of the psu in the other (so to speak). One squeezes the coolant in the reservoir (not visible, behind the radiator) and flicks the switch making sure the pump doesn't run dry (or not too long). Repeat process until reservoir is 75% filled all the while making sure you see no leaks in the process. If one does, stop the process, place bottle near drain and..well..drain.
Fix leak, and try again.
What really makes the process shine is to make sure no other component have power other than the pump and rad fans (and psu of course). That being said I've had, similar like Phil, my fair share of incidents and accidents. Live and learn.