Create a new website you can name this Dropdown or whatever name you’d like to choose.
Now go to Design view in Visual Studio and we can now drag in a Tool Script Manager.
Now that we have our handy bulleted list, Again we chose a simple list of Red, White, & Blue.
We are simple adding a Panel and to that a Bulleted list.After that we added a Drop Down Extender and set its properties and Target Control. NET AJAX control that can be attached to almost any ASP. For example: If you have a Text Box and a Panel control (with a checkboxlist), and you want to give the Text Box a drop-down menu, then just apply the Drop Down Extender to the Text Box and set the Drop Down Control ID to the Panel.Let’s start with a simple example of the AJAX Control.This is optional, we used it to make the example pop a little bit.
Next step is to add our content and today we are going to use a bulleted list just to keep things simple and neat. Name it whatever you’d like, just keep in mind your naming convention so you will recognize the ID when either styling or calling it at another time.