Is this your first time here?
Hi and welcome!
For full access to courses you'll need to take a minute to create a new account for yourself on this web site. Each of the individual courses may also have a one-time "enrolment key" your teacher has given you.
But first fill out the New Account form with your details (username can be a pseudonym). An email will be immediately sent to your email address. It contains a weblink to confirm your account.