Adding images to slider in Sydney

Hi. I am having difficulty adding my own images (up to 5 as indicated) to the slider.

I am accessing it via slider.php where I want to replace the images sources, but nothing seems to work. In fact, my whole site broke at one stage. I had to delete the theme and start over again.

Can you please assist in how to do this?

The code I am seeing with the theme image is:

if ( get_theme_mod(‘slider_image_1’, get_template_directory_uri() . ‘/images/1.png’) ) {
echo ‘<div class=“slide-item” style="background-image:url(’ . esc_url(get_theme_mod(‘slider_image_1’, get_template_directory_uri() . ‘/images/1.jpg’)) . ‘);"></div>’;

From image 3 onwards some of the code above is different or left out.

Please help me - this is the major function why I am using this theme in the first place.

Website link cannot be provided since it is currently developed on a local host.