How do you put detergent in this challenge extreme pressure washer?

Your machine is an inexpensive version, so there is an extra step in the soaping and rinsing process. First, fill the bottle all the way to the top. To soap, you have to take the wand off your pressure washer and install the bottle device. Soap down the surface you are washing using the sprayer/bottle configuration, then remove the bottle re-install the pressure end and rinse. The reviews are good on this unit when used for light duty cleaning. Good Luck