Redmine

Now i m using following Environment:
Redmine version 2.3.4.stable
Ruby version 1.9.3-p448 (2013-06-27) [i386-mingw32]
Rails version 3.2.13
Environment development
Database adapter SQLite

i want to migrate databases from follwing Environment:
Redmine version 2.4.1.stable
Ruby version 1.9.3-p231 (2012-05-25) [i386-mingw32]
Rails version 3.2.16
Environment production
Database adapter Mysql2

how to change databases SQLite to MYsql2 ?
previous i had used bitnami redmine on my local server but now i want to user on publically like redmine.mydomain.com

i had install redmine on mywindows server but i cann't migrate databases. how to its possible ?