Hi,
You need to add HTML to index.html and css to style.css, navigate to line 229 (style.css) and copy from

.img1 {
background:url(../img/1.jpg) no-repeat center center fixed;
filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src='../img/1.jpg', sizingMethod='scale');
-ms-filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='../img/1.jpg', sizingMethod='scale')";
}

and paste to create new class for slider