Install RailsInstaller.
Installation assumes the presence of rvm on your system. Otherwise, install rvm first.
After all prerequisites for your respective system have been met, clone the repository.
When you cd to the project directory, rvm will ask, "Do you wish to trust this .rvmrc file?" Respond with yes.
Then, from the root of the project directory:
$ bundle install
$ rake db:schema:load
$ rake db:seed
Then run it:
$ rails s
If all went well, it is now accessible from http://localhost:3000.