From Learn About the Ext JavaScript Library

I want to use the YUI-ext library and I'd like to know if my code is correct or if have other mode of use it

 Ext.onReady(function(){
       
           // Cria-se o DIV para a Barra da Área de Desktop:
           var myDIVBarraIniciar = document.createElement("div");
           myDIVBarraIniciar.setAttribute("id", "BarraDaAreaDeDesktop");
           myDIVBarraIniciar.style.height = "36px";
           myDIVBarraIniciar.style.position = "absolute";
           myDIVBarraIniciar.style.left = "0px";
           myDIVBarraIniciar.style.right = "0px";
           myDIVBarraIniciar.style.bottom = "0px";
           myDIVBarraIniciar.style.backgroundImage = "url(../Imagens/FundoBarraHMLive02.gif)";
       
           // So that the DIV is visible for the DOM, inserts the same in the BODY of the page: 

document.body.appendChild (to myDIVBarraIniciar);

           // Buttons objects of the YUI-EXT Are created and inside insert the same ones of the Bar of Desktop: 

           // **********
           var myDIVButton01 = document.createElement("div");
           myDIVButton01.setAttribute("id", "Button01");
           myDIVButton01.style.position = "absolute";
           myDIVButton01.style.left = "10px";
           myDIVButton01.style.top = "6px";
           myDIVBarraIniciar.appendChild(myDIVButton01);
           
           var myButton01 = new Ext.Button('Button01',{text:'Teste 01'});

           // **********
           var myDIVButton02 = document.createElement("div");
           myDIVButton02.setAttribute("id", "Button02");
           myDIVButton02.style.position = "absolute";
           myDIVButton02.style.left = "100px";
           myDIVButton02.style.top = "6px";
           myDIVBarraIniciar.appendChild(myDIVButton02);
           
           var myButton02 = new Ext.Button('Button02',{text:'Teste 02'});

           // **********
           var myDIVButton03 = document.createElement("div");
           myDIVButton03.setAttribute("id", "Button03");
           myDIVButton03.style.position = "absolute";
           myDIVButton03.style.left = "190px";
           myDIVButton03.style.top = "6px";
           myDIVBarraIniciar.appendChild(myDIVButton03);
           
           var myButton03 = new Ext.Button('Button03',{text:'Teste 03'});

       });
       
   </script>