High Pressure Hose Will Not Connect To The Pressure Washer

First, make sure that you are attempting to connect to the correct fitting. Sometimes customers try to attach the high pressure hose to the water inlet.
Next, the metal fitting on the high pressure hose with collar must be pushed into the water outlet by turning/twisting it as it is being pushed into the outlet. The o-ring can be coated with petroleum jelly to make it easier to slide in. When in far enough so the collar can be threaded on to the metal fitting threads, make sure to screw it on until it stops.