Edit in JSFiddle

$("#myform").buildForm({
    "action" : "index.html",
    "method" : "get",
    "elements" :
    [
        {
            "type" : "p",
            "html" : "You must login"
        },
        {
            "name" : "username",
            "id" : "txt-username",
            "caption" : "Username",
            "type" : "text",
            "placeholder" : "E.g. [email protected]"
        },
        {
            "name" : "password",
            "caption" : "Password",
            "type" : "password"
        },
        {
            "type" : "submit",
            "value" : "Login"
        }
    ]
});

<form id="myform"></form>