# Terminal
rails g thredded:install
rails thredded:install:migrations db:migrate db:test:prepare

# Gemfile
gem 'thredded'

# config/initializers/thredded.rb
...
Thredded.user_class = 'User'
Thredded.user_name_column = :name
Thredded.moderator_column = :admin
Thredded.admin_column = :admin
Thredded.layout = 'application'
Thredded.email_from = 'no-reply@example.com'
...

# routes.rb
mount Thredded::Engine => '/forum'

# application.html.erb
<div class="container">
  <%= link_to "Home", main_app.root_path %> | 
  <%= link_to 'Forum', main_app.thredded_path %> |
  <%= link_to "Users", main_app.users_path %> | 
  <% if user_signed_in? %>
    <%= link_to "Sign Out", main_app.destroy_user_session_path, method: :delete %>
  <% else %>
    <%= link_to "Sign In", main_app.new_user_registration_path %>
  <% end %>

  <%= yield %>
</div>

# stylesheets/application.scss
@import 'thredded';

.thredded--main-container {
  max-width: none;
}