To Display some Html content in Alloy Popup:

< aui:script >
function callPopup(){
AUI().ready('aui-dialog', 'aui-overlay-manager', 'dd-constrain', function(A) {
var dialog = new A.Dialog({
title: 'DISPLAY CONTENT',
centered: true,
modal: true,
width: 500,
height: 400,
bodyContent: "This is testing content inside the popup"
}).render();
});

}

</aui:script >