Validating login credentials against XML

Question

Hi i need help with a simple program that i am doing in VB.NET involving the use of XML.
let us assume that i have created a simple form with a two textboxes for entering Username and Password, and a Login button.

I have this simple XML file that stores the different username and passwords.

<?xml version="1.0" encoding="utf-8" ?>
<AuthenticationList>
<User id="01">
<Username>cs_helper01</Username>
<Password>cshelper01</Password>
</User>
<User id="02">
<Username>cs_helper02</Username>
<Password>cshelper02</Password>
</User>
<User id="03">
<Username>cs_helper03</Username>
<Password>cshelper03</Password>
</User>
<User id="04">
<Username>cs_manager</Username>
<Password>csmanager</Password>
</User>
</AuthenticationList>
 

when the login button is clicked, it needs to check the xml file storing the user and password. it needs to do validation of the textbox entries. but i do not know how to do this step. any help would be welcome!