I can rip some out of my page, but it's ASP and javascript os you'll need to translate.

Client side:
// Could have very large strings, so wrap in XML and post
var objXMLDoc = new ActiveXObject( "MSXML2.DOMDocument");
objXMLDoc.async = false;
objXMLDoc.resolveExternals = false;
objXMLDoc.loadXML( "" + strParams + "" + strUnassigned + "" + intRoundNo + "" + intGroupID + "")

// ...post...
var objSrvHTTP = new ActiveXObject( "MSXML2.XMLHTTP");
objSrvHTTP.open( "POST", gsPathCupComps + "Draws_Save.asp", false);
objSrvHTTP.send( objXMLDoc);

if ( objSrvHTTP.responseText == "True") {