Once the tour is ready to be translated, and you have commited the revised po template to the branch, you can start translating on launchpad.
Go to https://launchpad.net/ubuntu-tour. Then under "Get Involved", select "Help Translate".
Select the language you would like to translate.
Translate the strings which you know, sometimes translations will be available from other projects.
When you are done, scroll to the bottom and press save. Thankyou for contributing to the project.