Show red border on textbox on error
<p>I am trying to show an error by changing the color of the border of a text box. I have found a lot of posts on how to do it, but I have never done anything with 'Validators' so I am confused where to start, or where to put the code.</p>

<p><strong>Similar posts:</strong></p>

<p><a href="https://stackoverflow.com/questions/196859/change-text-box-color-using-required-field-validator-no-extender-controls-pleas" title="Post 1">Post One</a></p>

<p><a href="https://stackoverflow.com/questions/1301508/change-textboxs-css-class-when-asp-net-validation-fails">Post Two</a></p>

<p>My main question(s) are, where do I put the JS code? And secondly, how do I call the code?</p>

<p><strong>Current Code</strong></p>

<pre><code> If TicketNumber.Text = String.Empty = True Then
        NotificationLabel.Text = "Ticket Number must be filled out"
        Exit Sub
    End If
</code></pre>