Redmine

I have been installed redmine2.4.2, but i wants install the latest version of redmine, after installation i found its version is 2.4.2. So i am not happy with this.
I installed the redmine by folowing commands:
sudo apt-get install apache2 libapache2-mod-passenger
sudo apt-get install mysql-server mysql-client
sudo apt-get install redmine redmine-mysql
sudo gem update
sudo gem install bundler
sudo gedit /etc/apache2/mods-available/passenger.conf

Add the following line:

<IfModule mod_passenger.c>
PassengerDefaultUser www-data
PassengerRoot /usr
PassengerRuby /usr/bin/ruby
</IfModule>

sudo ln -s /usr/share/redmine/public /var/www/html/redmine
sudo gedit /etc/apache2/sites-available/000-default.conf

Add the following line:
<Directory /var/www/html/redmine>
RailsBaseURI /redmine
PassengerResolveSymlinksInDocumentRoot on
</Directory>

sudo service apache2 restart
sudo touch /usr/share/redmine/Gemfile.lock
sudo chown www-data:www-data /usr/share/redmine/Gemfile.lock
sudo service apache2 restart
http://127.0.0.1/redmine

Now i checked the redmin information i found:
Environment:
Redmine version 2.4.2.stable
Ruby version 1.9.3-p484 (2013-11-22) [x86_64-linux]
Rails version 3.2.16
Environment production
Database adapter MySQL
SCM:
Git 1.9.1
Filesystem
Redmine plugins:
no plugin installed

Please help me to upgrade redmine2.4.2 to redmine3.3.1.