Many times you will find yourself working with a Joomla template that you didn't design. Even if the template was custom design for you, you may not know where all the module positions are. You may also be trying to find out how to edit a module, but can't figure out where it is.
Fortunately, the folks at Joomla thought of this, so there is a way to find out. To find out what and where your module positions are, add this to the end of your website address:
?tp=1
Example: http://www.yoursite.com/?tp=1
If you are looking at a page that already has variable, simply add &tp=1 to the end of the variables.
Example: http://www.yoursite.com/index.php?option=com_content&id=1&tp=1
The result is that you will see your website with an overlay that contains grey boxes showing the position, name and type of module. They will look something like this:

It's that simple...

