email verification in e commerce application

I have been developing an e-commerce application(Online shopping center)for my B level final project.I am using JSP(in Netbeans),Mysql,EJB(Session bean) and Servlet for developing the application.I am following Netbeans ecommerce tutorial(https://netbeans.org/kb/docs/javaee/ecommerce/intro.html).I want the email verification feature in my app.The requirement is that when the user clicks on purchase button,he/she will be redirected to the email verification page.This page contains two text boxes for entering email Id and password.The page also have two options(radio buttons),one is for existing customer and the other is for new user.If the user selects newuser radio button,he/she will be redirected to a signup page.Here,he will provide signup data which will be stored in the customer table in the database.If the user selects existingcustomer radio button,the email id and password provided by him will be compared with the email ids and password in the customer table one by one.If a successful comparison is found, he will be redirected to the checkout page.The code should be written in sevlet using session bean. I have no idea.Please help me.