You have to manually edit style.css file.
.promotional-block2{
background: url(images/img33.jpg) no-repeat;
background-size: cover;
position: relative;
padding: 96px 0;
background-attachment: fixed;
}
/*our-services section style*/
.our-services{
background: url(images/img30.jpg) no-repeat;
background-size: cover;
position: relative;
padding: 69px 0 67px;
text-align: center;
background-attachment: fixed;
}
/*promotional block style*/
.promotional-block{
background: url(images/img23.jpg) no-repeat;
background-size: cover;
position: relative;
color: #fff;
padding: 120px 0;
background-attachment: fixed;
}
