The thing to understand about DNN is that the whole system is based on a set of templates and user defined modules whose layout is determined at runtime by values stored in a SQL database.
As such therefore - to make changes to the content of a DNN site you dont edit default.aspx.
But instead you make changes to the relevant template or user module concerned.
>>> For your specific request - that is getting rid of the copyright statement - the easiest way is to simply turn of the switch in the database that causes the copyright statement to be displayed.
This switch is located on the HOST Menu -> Host Settings
On that page you will find a checkbox "Show Copyright Credits" = turn it off and you are done.
>>>
As to exactly how this works. WHEN default.aspx is called:
1. it looks to see what skin your site has selected
This skin contains all the info for the default layout of your site.
The skin is effectively a big user control defined as an ascx file that contains the HTML markup that defines where all the main elements of your generic page layout appear.
In reference to your original question - the skin .ascx file currently in use on your site will contain a tag that looks something like this:
<dnn:COPYRIGHT runat="server" id="dnnCOPYRIGHT" />
This is the dnn element that is used to display the copyright message.
So you could also create your own skin and delete this tag - to get rid of the copyright message.
Westa