new.html.erb

<h1>Registration</h1>
<%= error_messages_for :user %>
<div id="stylized" class="myform">
	
		<%= form_for(@user, :action => resource(:users)) do %>
		    <label>Username
					<span class="small">At least 4 characters</span>
				</label>
				<%= text_field :login %>
				<label>Password
					<span class="small">At least 6 symbols</span>
				</label>
				<%= text_field :password %>
				<label>Confirm password
					<span class="small">Retype your password</span>
				</label>
				<%= text_field :password_confirmation %>
				
		   	<button type="submit">Register</button>
				<div class="spacer"></div>
		<% end =%>
</div>

user.rb

        validates_present   :login
        validates_is_unique :login, :message => "Username is already taken !"

users.rb

  def new
    only_provides :html
    @user = User.new
    display @user
  end

  def create(user)
    @user = User.new(user)
    if @user.save
      redirect resource(@user), :message => {:notice => "User was successfully created"}
    else
      render :new
    end
  end