Redmine

hi guys,
i'm sory for such a newbie question but i have problems createing the database struc with rake db:migrate RAILS_ENV="production". You can barly call me a developer more like a Business Engineer who is stunned by your outstanding work..
My goal is just to setup a virtual machine with redmine running to give my company a demonstration (and hopefully convince them to implement it in our workflow)

here is what i did so far.

create virtual machine Kubuntu 8.04 using virtulbox host windows xp
installed rails 2.0.2 (ruby 1.8.6 already installed)
installed mysql 5.0
created the database
checked out redmine 7.0 (checkout folder is /home/sebastianjonas/redmine-0.7)

now im stuck with creating the initial database structure.
i dont know in wich folder i should execute rake db:migrate RAILS_ENV="production"
i tried it in /home/sebastianjonas/redmine-0.7 with the following result:

rake aborted!
no such file to load -- initializer
/home/sebastianjonas/redmine-0.7/Rakefile:4:in `require'
(See full trace by running task with --trace)

any tips where to execute the command (kubuntu) or if i missed any installstep?
thanks in advance.

Best regs
Sebastian