session creation

app/controllers/application_controller.rb

@@ -1,2 +1,10 @@
 class ApplicationController < ActionController::Base
+  helper_method :current_user
+  helper_method :logged_in?
+  def current_user
+    User.find_by(id: session[:user_id])
+  end
+  def logged_in?
+    !current_user.nil?
+  end
 end

app/controllers/sessions_controller.rb

@@ -3,6 +3,11 @@ class SessionsController < ApplicationController
   end
 
   def create
+    @user = User.find_by(username: params[:username])
+    if @user && @user.authenticate(params[:password])
+      sessions[:user_id] = @user.id
+    end
+    redirect_to '/welcome'
   end
 
   def welcome

app/controllers/users_controller.rb

@@ -1,5 +1,6 @@
 class UsersController < ApplicationController
   def new
+    @user = User.new
   end
 
   def create