When working with divs in HTML, keep in mind that they will naturally flow within the DOM. By default, they will take up 100% of the width of their parent container and their height will be determined by the non-floated content inside them. You can use margins to create space between divs as needed. Divs have a default position of static, but if you want list styles, consider using <li> elements with display:list-item instead of display:block.
For example:
HTML:
<div class="comments"> Some really long comments </div>
<div class="foo"> Something that should appear below the comments </div>
CSS:
.foo {
margin-top : 50px;
}