Your request is about custom work and out of scope of JA Support but you can follow my suggestion
1) Hide logo
Open templates/ja_purity_ii/css/template.css file
from
h1.logo a {
background: url(../images/logo.gif) no-repeat left;
display: block;
height: 79px;
width: 207px;
}
change to
h1.logo a {
background: url(../images/logo.gif) no-repeat left;
display: block;
height: 79px;
width: 207px;
display: none;
}
2) Upload image banner include logo of your site here
Open templates/ja_purity_ii/blocks/head.php file
from
<style type="text/css">
#ja-header .main {
background-image: url(<?php echo T3Path::getUrl('/images/header/header'. rand(1,3).'.jpg'); ?>);
}
</style>
With image path randomize: templates/ja_purity_ii/images/header/header1.jpg, header2.jpg, header3.jpg
