There are free resources available for students and people new to the cybersecurity field, including:
This resource explains how capture the flag competitions work and includes a list of competitions and ideas on how to prepare.
Github put together this list of tutorials, software, resources, frameworks and libraries to help people new to CTF competitions as well as veterans.
This forum hosts real-time questions and answers to questions about competitions and strategies.
This practice zone includes labs built for beginners to test cybersecurity skills.