Where can I learn more about robotics?

Hello, where can I start learning more about robotics in particular so that I can take part in RoboCupJunior Rescue Line? What books or websites do you recommend?

I personally am not aware of any online materials. I would recommend connecting with people already participating in RCJ. Try finding organizations in your country, or maybe even around the world if you are able to establish contact with them.
Best of luck,