ruby migration

Hi ,

I am new to the ruby on rails.
I am having some problem with migration on ruby.
any one could explain....
  1. what db migration on ruby.
  2. how to create migration.
  3. how to migrate the "db" development to production ( now i have
create needed to file for migration(for creating new tables) .. i
did... "rake db:migrate" command.. it says nothing(no error/ no
success command, And also no changes was made in DB)

i have some idea about 1 & 2. but i have no idea about 3. Please help

Thanks & Regards,