Thanks for your interest in Mystery Writing! When you go to the homepage www.mysterywriting.com, you will see an option to claim a free trial.
If you are new to the system, follow the sign-up flow and you will be sent an email verification email (if you do not see it in your inbox after a few minutes, check your SPAM folder). After verifying your email, you can complete your account setup by selecting your school from the drop-down.
To learn more, check out this article:
If I already have a Mystery Writing account, how do I access Mystery Science?