To register on OpenClassrooms , it's easy!
Once on the homepage of the site, simply click on "Sign Up", in the top right.
A pop-up opens, which allows you to register, either in one click via your Facebook or Google account, or via a form to fill. If the pop-up does not appear, be sure to disable AdBlock or any strict plug-in preventing it from being opened.
The credentials will be sent to the email provided.
Warning, if the email with the credentials is not in your email inbox, check your spam or "Promotions" folder.