New to RVing... need help with fresh water filling

The very first thing I did was download that very manual.

OK one line definitely goes to the fill point... when you tug on it at the pump it moves at the other end. So the question I guess I have is: how is the water supposed to get into the tank? Is it supposed to go thru the pump in the direction that is opposite from the normal flow direction? Doesn't the pump have a check valve to prevent water from flowing "backwards"? There are no other openings on the tank for water to enter