Step 1: Decide what you want out of your top.
Step 2: Plan out in your mind where you will top to get step one.
Step 3: Take scissors and cut stalk right above the last node/s you want to keep.
Step 4 (optional): If your cutting is big enough, why not make her a beautiful clone?
Its honestly not hard at all, and you will only hermie the plant if you screw up and keep slicing the stalk multiple times. The trick to topping is where to make the cut. If you do not know where you want to make the top, or dont have much information about such things and this is your first grow then i advise you to try topping just one plant and letting the others grow naturally. If you would still like a video demonstration im sure i can find something real quick.