Moon landing, how does it help the exploration of Mars ?

Using the known water on the Moon, hydrogen and oxygen can be processed into rocket fuel. The unfiltered Sun can provide energy to do it. The water also allows long term stays and bases for humans. The lower gravity on the Moon and lack of air resistance makes lifting payloads easier.

Also, the experience gained in survival in the Moon's hostile environment will provide needed technology and techniques for the long journey and stay on Mars.

Sending men to mars requires lot of preparations including sending advanced cargo crafts with fuel,water and oxygen. The gravity is less moon and so rocket size can be reduced much if we assemble it in lunar surface.