title: How can i give message alert box in asp.net
body: <p><strong>how can i give message box alert in asp.net</strong> Webpage
  By checking the username and password by membership in 'if' statement and in 'else' i should display the alert box as"enter valid username and password"(i checked the 'if' but i don't know how to give alert message in 'else')</p>
  
  <pre><code>if (Membership.ValidateUser(txtUserName.Text, txtPassword.Text))
             {
  
             }
             else
             {
                 // Here i have to display message box alert
             }
  </code></pre>
  
  <p>Please  help me to solve this issue as soon as possible. </p>