Magento – How to add Coupon Code Section In mini cart like in the shopping cart

I have searched a lot on google but didn't get the solution for this.
I new to Magento, can any help me to how to add the coupon code section in Mini cart of magento.
Like the Below Example:

I have added this in items.phtml

<?php $getCouponCode = Mage::getSingleton('checkout/cart')->getQuote()->getCouponCode(); ?>
                    <form id="discount-coupon-form" action="<?php echo $this->getUrl('checkout/onepage/coupon')?>" method="post">
                    <!-- <label for="coupon_code"> <?php //echo $this->__('Enter your coupon code if you have one.') ?></label> -->
                    <input id="coupon_code" name="coupon_code" value="<?php echo $getCouponCode; ?>"/>
                    <?php  if(strlen($getCouponCode)) { ?>
                    <button type="button" onclick="updateminiCoupon(2); return false;" value="<?php echo $this->__('Remove Coupon')?>"><span><?php echo $this->__('Remove Coupon') ?></span></button>
                    <?php } ?>
                    <button type="button" onclick="updateminiCoupon(1); return false;" value="<?php echo $this->__('Apply Coupon')?>"><span><?php echo $this->__('Apply Coupon') ?></span></button>
                    </form>

and js :

<script type="text/javascript">
//<![CDATA[
function updateminiCoupon(reqid) {
    //alert('d');
    var reqid;
    if(reqid == 2) {  $('coupon_code').setValue('');  }
    $('discount-coupon-form').request({
        method: 'post',
        onComplete: payment.onComplete,
        onSuccess: payment.onSave,
        onFailure: checkout.ajaxFailure.bind(checkout),
    })
}
//]]>
</script>

by reference link:
http://www.endreywalder.com/blog/add-coupon-code-form-to-magento-onepage-checkout-review-step/

Check the Reference site : http://www.nykaa.com/