Image with size 220×700 belongs to module called ‘Onepage 7’: http://static.joomlart.com/images/userguide/ja_templates/ja-appolio/onepage7-back.png
As you can see each column will be set with a background image, if you open the file: /templates/ja_appolio/css/template.css at approx line 6120, you will see this:
.col1 {
background: url("../images/background-col1.jpg") no-repeat 0 50%;
}
.col2 {
background: url("../images/background-col7.jpg") no-repeat 0 50%;
}
.col3 {
background: url("../images/background-col5.jpg") no-repeat 0 50%;
}
.col4 {
background: url("../images/background-col4.jpg") no-repeat 0 50%;
}
.col5 {
background: url("../images/background-col3.jpg") no-repeat 0 50%;
}
.col6 {
background: url("../images/background-col7.jpg") no-repeat 0 50%;
}
.col7 {
background: url("../images/background-col2.jpg") no-repeat 0 50%;
}
.col8 {
background: url("../images/background-col1.jpg") no-repeat 0 50%;
}
.col9 {
background: url("../images/background-col2.jpg") no-repeat 0 50%;
}
.col10 {
background: url("../images/background-col3.jpg") no-repeat 0 50%;
}
.col11 {
background: url("../images/background-col4.jpg") no-repeat 0 50%;
}
.col12 {
background: url("../images/background-col5.jpg") no-repeat 0 50%;
}
You can change above with your own images.
In the same ‘template.css’ file, you look at line of 5553, you will see this css rule:
.t3-footer .container > .mask {
content: "";
width: 100%;
height: 100%;
position: absolute;
display: block;
top: 0;
left: 0;
background: url("../images/bg-footer.jpg") no-repeat center center;
background-size: cover;
opacity: 0.1;
filter: alpha(opacity=10);
}
This is background image in footer with dimension of 2800×1867 as you mentioned, you can change to your own image here.