Very embarrassing question. I have a Fuji mini-pump that I haven't used before. It's one of those pumps that reverses to presta or schrader. The instructions are just some illustrations. I have it set for a Schrader valve but what do I do now, lol! After I reversed it, I assume I should screw back that cap before inserting it on top of the valve. That didn't work. I took it off and placed it on top of the valve but that doesn't seem right either. I put it on top of the valve, air comes out and I don't even know how it's supposed to "lock into place."

I'd like to avoid driving to the LBS. I'm too mortified to explain the problem.