When putting the vinegar into a front load washing machine you put the vinegar into the fabric softener dispenser.
When you put the vinegar into the fabric softener dispenser the vinegar will then be added to the washing machine and laundry when the washing machine starts the rinse cycle.
Add the white vinegar to the fabric softener dispenser and up to the top level of the dispenser.
The vinegar helps to remove any detergent and soil that is clinging to fabric clothes feeling soft and clean.
The vinegar also cleans out the washing machine as well.