Add the following code in your site, inside the head tag:

                                                                                <script>
                                                                                  function SocialShare(url) {
                                                                                      window.open('https://banglasathi.com/share?url=' + url, '', 'height=600,width=800');
                                                                                  }
                                                                                </script>
                                                                                

Then place the share button after changing the URL you want to share to your page HTML:

<button onclick="SocialShare('http://yoursite.com/')">Share</button>

Also you can use this code to share the current page:

<button onclick="SocialShare(window.location.href)">Share</button>

Example: