login_form.html.erb

<h1>Login</h1>

<%= form_tag author_sessions_path, method: :post do %>
  <div class="field">
    <%= label_tag :username %>
    <%= text_field_tag :username %>
    <br/>
  </div>
  <div class="field">
    <%= label_tag :password %>
    <%= password_field_tag :password %>
    <br/>
  </div>
  <div class="actions">
    <%= submit_tag "Login" %>
  </div>
<% end %>
<%= link_to 'Back', articles_path %>