We've got a template that has 5 or 6 HTML modules in the main container area.  Could do with moving these about or adding ones in the middle, not just at the top or bottom.  Is there a way to order the modules or just move them up or down? 

I've clicked around the admin area for ages, but I can't find a way to do change the order.

As admin, and with the page in edit mode, you should see a small control on each module (location may vary depending on the skin you are using).   Mouse over it and you should see a menu such as for module settings, but below that are options for moving the module up, down, in position, or to other panes.      Alternatively, place your mouse over the module at the title area, and drag and drop to where you want it.