A/C Question

Just bought the recharge kit for my '87 5th.
It has a slow leak.
If I refill it, it lasts the whole season. But this is the first time that "I'm doing it"
I know the deal with the gauge and the cans (upside down.. Don't pierce till ready, etc.)
Just want to double check which side to put the juice in
Car running? A/C on? What setting? Hi, low?
Thanks.