Set Selection of htmlb Dropdown

How do i set the htmlb Dropdown selection in the Javascript with the value selected? It getz populated with Model from bean.

<hbj:dropdownListBox

id = "myDdBox1"

disabled = "false"

model = "myBean.model"

selection = "<%=myBean.getSelection()%>"

jsObjectNeeded = "TRUE"

onClientSelect = "Event()">

</hbj:dropdownListBox><br><br>

<script>

var funcName = htmlb_formid+"_getHtmlbElementId";

func = window[funcName];

var dropdown = eval(func("myDdBox1"));

what shud i do here??

</script>

Shud i add this also?

var form = document.all(htmlb_formid);

form.submit();