Move Church

In John chapter 3:1-15, Nicodemus; a member of the Pharisees and a ruler of the Jews, approaches Jesus attempting to discover who he was and understand him better, but Jesus tells Nicodemus he can't understand him because he doesn't have the ability to assess the evidence about him properly...and neither can you or I or anyone, apart from being 'born again'. We cannot see, or enter the kingdom of God without being born again, so what does this mean and how is it achieved?