The easiest way is to setup the content inside a div and display that inside the dialog. So instead of passing the dialog content as a string like you tried it:
$('<p>This is my Dialogue</p>').dialog({ ... });
Setup the dialog content like this:
<div class="popup">
<p>This is my Dialogue</p>
<!-- Add whatever code you like here to be displayed-->
<textarea></textarea>
<select>
<option value="1">Option 1</option>
<option value="2">Option 2</option>
<option value="3">Option 3</option>
</select>
</div>
And bind the dialog to that element:
$('.popup').dialog({
buttons: {
"Submit": function () {
//Your submit handler
}
},
title:'Your title',
width: 600,
height:300,
});
Here is a basic working example: http://jsfiddle.net/W7zvZ/. A more complex example of using forms can be found on the jQuery UI Dialog Docs page (just click on the View Source link here to see the code behind it).