How to customize the order confirmation email generated from company’s web site

`var CONTEXT = nlapiGetContext(); //get the current context
var executeScript = true;

function OrderConfirmEmail()
{
    nlapiLogExecution('DEBUG', 'Process Error', "hi");
    var stExecType = CONTEXT.getExecutionContext();
    if(stExecType != 'webstore')
    {
      try
      {
        return true;
      }
      catch(e)
      {
        nlapiLogExecution('ERROR', 'e', e);
        return true;
      }
    }
    try
    {
        var orderid = nlapiGetRecordId();
        var order = nlapiLoadRecord('salesorder',orderid);
        var detail  = getOrderDetail(order);

        if(detail.tranid == null)
        {
            var order = nlapiLoadRecord('salesorder',orderid);
            detail  = getOrderDetail(order);
            SendEmail(detail);
        }
        else
        {
            SendEmail(detail);
        }
    }
    catch(error)
    {
        if(error.getDetails != undefined)
        {
            nlapiLogExecution('ERROR', 'Process Error', error.getCode() + ': ' + error.getDetails());
            throw error;
        }
        else
        {
            nlapiLogExecution('ERROR', 'Unexpected Error', error.toString());
            throw error;
        }
    }
}

function SendEmail(detail)
{
    var htmltext = '';
    htmltext = htmltext + getHead(detail.entity);
    htmltext = htmltext + getTemplateHeader(detail.entity);
    htmltext = htmltext + getStatus(detail.tranid,detail.entity);
    htmltext = htmltext + getOredrInformation(detail,detail.entity);
    htmltext = htmltext + getShippingDetail(detail,detail.entity);
    htmltext = htmltext + getOrderDetailEN(detail);
    htmltext = htmltext + SuggestedProduct(detail.entity);
    htmltext = htmltext + thankYouMessage(detail.entity);
    htmltext = htmltext + services(detail.entity);
    htmltext = htmltext + getTemplateFooter(detail.entity);
    htmltext = htmltext + getTemplateFoot(detail.entity);

    nlapiSendEmail('18', detail.email, 'Order Confirmation Email', htmltext);
}