So ...

In most cases, you would probably want to open your forum for new registrations.

To do that you need to open your website for registrations.

Go to Settings => General, and check the box next to “Any one can register” to allow registrations on your website:

Important note: here and now I won't waste your time with technical details, but you need to know, that allowing open registrations could be a bad idea if you don't have a reliable and well-configured security plugin/solution in place! Sometimes is just better and safer to approve the newly registered users manually ...

With that having said ...

If your site is open for registration, the first thing that your forum participants would look for is a registration page.

So create a new page, give it a title, e.g. Register, add the [bbp-register] shortcode and publish the page.

Another page your users would need is the Lost Password recovery page. You can create it using the [bbp-lost-pass] shortcode.

Now you need to provide a login solution ... Relax, bbPress comes with a handful of widgets.

Go to Appearance => Widgets, drag and drop the bbPress Login Widget to your sidebar (or any other widget area), enter the URLs for the Registration and Lost Password pages and save the widget:

As a result, a login form will appear in your sidebar.

Depending on your theme, the registration and lost password recovery links could appear on your login widget or in the main menu ...

And of course, logged in users will see their usernames and a log out link instead of the form.

OK. Let's move forward to the last lesson to discuss about forum settings ...