You soak the jiffy pellets in PH balanced (6.5-7.0) water for a half hour or so and they expand.
Remove the excess water once they’ve expanded. You want the environment wet, but not soaked.
Put them in a humidity dome. I’ve got a factory made one, but you can make them out of clear drinking cups taped on top of each other as well.
As soon as they start busting out of the ground I put them under fluorescent light. I like sooner rather than later because if I let them get away they try stretching up to find light and the stems might get too leggy.
The good thing about peat pellets is that you never have to switch the plant out. You just plant the pellet into the next medium (dirt or hydro).