In order to use this dialog you need to have a RadWindowManager on the page.
The minimum required to show a RadPrompt is the content string and a callback function. Please have a look into the following code.
ASPX:
<buttononclick="radprompt('What is your Name?', promptCallBackFn); return false;">
Display Prompt Box</button>
JavaScript:
<script type="text/javascript">
functionpromptCallBackFn(arg)
{
alert("The name you entered is : "+ arg);
}
</script>
If you want to display the RadPrompt from code behind, you can try the following code.
C#:
RadWindowManager1.RadPrompt("What is your Name?", "promptCallBackFn", 350, 100, null, "Enter Name", "42");