How to return from external link to android studio phone gap?

Here i want to give a back link ,which will go to my android phone gap and required section of app will open ,according to back link.But here i am facing some difficulties to do this one.Its not working at all,where i am doing wrong ,please suggest me.Thank you in advance.

Here in anchor link i have given the back url to my app,but here i am not sure of it.Is it the proper way or not.

<div class="inner-area">
    <div class="wrapper">
        <div class="inner">                     
            <?php echo $this->Session->flash() ?>
            <div class="welcome_holder login" style="float:left;width:100%;">                        
                <h2>Thank you for purchasing our package.<br/>
                    <a href="file:///android_asset/www/package.html"><< Back To App</a></h2>  
            </div>
        </div>       
    </div>
</div>