If you are not yet registered, registration only asks you for a valid email and password. It takes less than a minute and you can start using the full site functionality immediately.
If you do not know your password, click on "forgot password?". It will send you a link via email which will allow you to enter a new password. It is super easy and only takes a minute.
After you log in, you can change your user settings by clicking on the link in the top right corner of the page.
The tour is specific to each page. Take the tour on the main page for guidance regarding general navigation.