If you want to open current slider image URL in new window, you just need to add custom script in your website:
jQuery(function ($) { $('.nk-slider').on('click', function () { var url = $('.nk-slider-current-slide').css('background-image'); url = url ? url.replace('url(','').replace(')','').replace(/\"/gi, '') : false; if (url) { window.open(url); } }); });
Please, read documentation of your theme and basic WordPress documentation: