It's absolutely free and comes with the MyBB installation files. Download the pack and open -> upload->install->resources - you have 2 files here : mysql_db_inserts and mysql_db_tables that contain the whole DB structure.
I didn't really install it I just got it from some site and it made it for me. I wanna put it onto my site tho.
Don't exactly understand what you mean there. You want to install a MyBB database or transfer it from one website to another ? If your question is how can you copy it then - go to phpmyadmin select the database and export it.