First starting problème

I try to create a first little function. But when i'm try to create the obj, mi browser say me: 'Active' is undifine.

Mi sintax:

var obj = new Active.HTML.DIV;
obj.setContent("Hello, World!");
document.write(obj);

in fact when i type new"Space"... it's doesnt found the Active class.

do you have an idea?