You get 3 lbs/gallon of refill. So program accordingly. Then pour 2-3 gallons of water into the water in the salt tank, not into the salt. Wait 2 hours and do a manual regeneration. Don't use water during a regeneration.
I suggest keeping a spare bag (or 3-4) of solar crystal salt by the tank and keeping the tank half full. That makes you check the level more frequently and that prevents running low or out of salt. If you run low/out and get hard water through the unit, then you need to do 2 manual regens at 15 lbs/cuft of resin (23lbs for 1.5') with no water use during or between them so as to get all the resin regenerated.
If your grid has legs that allow salt down into them and thereby into the water, you don't need the water to come up over the grid.