You can use WordPress’ built-in registration feature or use a plugin.

For the WordPress default registration method, go to Settings -> Appearance and check Anyone can register. Make sure you don’t set Administrator as New User Default Role.

Now, you need the Register and Log in links. You can go to Widgets and put the WordPress Meta box in your sidebar or footer, but that will add extra links which you might not want. You could just use the registration and log in links separately, and add them in another place, like your menu or something:

• https://yourdomain.com/wp-login.php
• https://yourdomain.com/wp-login.php?action=register

This method will let users log in through your admin area, though. If you want a custom registration and log in page, you’ll have to use a plugin of your choosing.