When using OxiClean powder in a front load washer you put the OxiClean powder in the drum directly before or after adding the clothes.
I usually add the clothes and then add the detergent and the OxiClean when using it directly to the drum which works great.
You can also add some OxiClean Powder to the detergent in the same detergent drawer at the same time if your washing machine has a detergent drawer.
Add 1 scoop (25 g) of the OxiClean powder to the detergent in the washing machine drawer in the main wash cycle.
For very heavy soiling use 2 scoops.
OxiClean themselves recommends adding the OxiClean directly to the drum of the washing machine which works great in both top load washing machines and front load washing machines.
The below information is from OXiCleans Website on how to use OxiClean powder in a washing machine.
(Add OxiClean Versatile Stain Remover directly to the drum before adding clothing.
Don't worry about powder going through the little holes in the drum.)
OxiClean is a Versatile Stain Remover in a powder form that is activated when added to water (warm or hot water work best).
Oxygen is released and targets the stains, rather than the fabric, removing many tough stains on water-washable clothing, carpet, upholstery, and hard surfaces both inside and outside the home.
OxiClean Versatile Stain Remover is not designed to be used as a detergent.
Instead OxyClean is a laundry booster and is designed to be used with a laundry detergent to help boost cleaning, stain removal and whitening/brightening.
OxiClean cannot be used on wool, silk, leather or anything else that cannot be washed with water.
It also is not recommended on rust and other metallic stains because of the oxidation process.