Invite all the people who might be interested in your trip project: other organisers, participants and followers. All you need to do is click on the "invite to join" button from any of the pages dedicated to your trip project, and enter all these people's names or email adresses.

If you are interested in a school project and would like to join it, just send a request to one of the organisers. Do not hesitate to specify the reasons of your request in your message, for instance if one of the participants is your third cousin. Knowing who you are will be very helpful to them.