How can I move photos around

Move your code, not the image.

<!doctype html>
<html lang="end">
<head>
<meta charset="utf-8">
<title>CSS Grid Evenly Distributed Layout</title>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
html { font-size: 16px }
body {
font-family: "Lucida Grande", "Lucida Sans Unicode", "Lucida Sans", "DejaVu Sans", Verdana, "sans-serif";
font-size: 1.5rem;
margin: 0 auto;
max-width: 56em;
padding: 1em 0;
}
.grid {
/* Grid Fallback */
display: flex;
flex-wrap: wrap;
/* Supports Grid */
display: grid;
grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
grid-auto-rows: minmax(150px, auto);
grid-gap: 1em;
}
.module {
/* Demo-Specific Styles */
background: #eaeaea;
display: flex;
align-items: center;
justify-content: center;
height: 200px;
/* Flex Fallback */
margin-left: 5px;
margin-right: 5px;
flex: 1 1 200px;
}

/* If Grid is supported, remove the margin we set for the fallback */
@supports (display: grid) {
.module {
margin: 0;
}
}
</style>
</head>

<body>
<div class="grid">

<div class="module">2</div>
<div class="module">3</div>
<div class="module">4</div>
<div class="module">5</div>
<div class="module">6</div>
<div class="module">7</div>

<div class="module">1</div>

<div class="module">8</div>
<div class="module">9</div>
<div class="module">10</div>
<div class="module">11</div>
<div class="module">12</div>
<div class="module">13</div>
<div class="module">14</div>
<div class="module">15</div>
</div>
</body>
</html>

Dreamweaver is not a page layout program like InDesign. You don't have the option to drag images around a page to create a layout. The program, for better or worse, assumes you understand HTML and CSS, and to a lesser extent Bootstrap and Javascript. Without an understanding of the basics, it's going to be tough to get your layout to do what you want.

If you understand how to work with HTML and CSS, look into Flexbox and Grid to create your layouts, then fill in the spaces with your images and text. 

Flexbox: https://www.w3schools.com/css/css3_flexbox.asp

Grid: https://www.w3schools.com/css/css_grid.asp

If you want to work with one of the buillt-in Responsive Bootstrap Starter pages: 
https://helpx.adobe.com/dreamweaver/using/bootstrap.html

That will get you started, but Bootstrap is a very, very large framework and to get the most out of it, you'll need to learn everything you can about the pre-built CSS classes within the framework. Whatever version you ultimately use, there is a ton of info online to explain what everything is and how to work with it.