add user model

app/models/user.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: users
+#
+#  id         :bigint           not null, primary key
+#  email      :string           not null
+#  first_name :string           not null
+#  last_name  :string           not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+# Indexes
+#
+#  index_users_on_email  (email) UNIQUE
+#
+class User < ApplicationRecord
+  validates :first_name, :last_name, :email, presence: true
+
+  def full_name
+    "#{first_name} #{last_name}"
+  end
+end