this is my code please give me hits to add line

{
xtype: 'linechart',
id:'storeID',
minorTickSteps: 1,
theme: 'Green',
store: storageStore(),
yField: 'storage',
url: '../js/ext-3.4.0/resources/charts.swf',
xField: 'date',
xAxis: new Ext.chart.CategoryAxis({
title: 'Date'
}),
yAxis: new Ext.chart.NumericAxis({
title: 'Storage Used (K',
stackingEnabled: true //this is for data range in data base regarding graph by naresh
}),
tipRenderer : function(chart, record){

return Ext.util.Format.number(record.data.storage, '.000000') + ' KB storage used in ' + record.data.date;
},
listeners: {
beforerefresh: function(chart) {
return Ext.isDefined(chart.swf.setDataProvider);
}
},
extraStyle: {
xAxis: {
labelRotation: 0
},
yAxis: {
titleRotation: -90
}
}
}
thanks naresh