My mother gave me a pressure washer for christmas last year. It was hers, and gently used. Unfortunately, she had a quick disconnect system for her garden hose.
I went in to Peavey Mart and purchased a few fittings that I "thought" I needed. Unfortunately, when I got home, none of them worked for what I needed. So I had to make a 2nd trip to Peavey Mart. But I made sure I brought the pressure washer with me.
I talked with the staff, and they showed me exactly which fittings I needed to get going.