Registering your bike is important if you want to enjoy all the benefits of the Mondraker warranty & obtain the lifetime warranty against breakages for all our current frames. It will also be used as a proof of ownership should there be a problem with the warranty process and will generate a registration of the serial number in case of the bike being lost or stolen.
You can find it on the down tube
Or on the bottom of the bottom bracket
This size table is only an estimation, the optimum frame size depends on your personal preference and riding style