You can also put smaller divs inside bigger divs like this. This is how I do the character boxes on my characters page - they are all sidebar divs with links and images in them.

If you put in more than one, they'll sit next to each other until they run out of room, at which point they'll start going vertically.

To make them stay the same height, you can add a height code in as seen here. See how some of these have a scroll bar? That's because it reached its max height. If max height is a number, this can happen. If max height is set to "auto," the divs will just stretch with content.