There we go. First steps in upgrading (or should I say migrating?) to Drupal 8. Drush is an incredible valuable tool, so this will be basically my first step.
Install the last version of drush, at least Drush 7 which includes support for Drupal8. If you already have drush and don't want to play with current versions, you can download drush 7 via git, and place it in /usr/local/drush-7, for example. Then, create a symlink like that:
ln -s /usr/local/drush/drush /usr/local/bin/drush7
This will create a second version to play safely. Now you also need to install composer:
curl -sS https://getcomposer.org/installer | php
and then, run install inside the new drush folder.
More information about next steps can be found here (basically information about Migrate module, which I will need to study in order to achieve the next steps):
The last steps will be... starting to develop in Drupal 8 :-):