Quotehow can I edit the header & footer,
- You can search the forum as this has been discussed many times. In short, you can edit your template.html.
For
Quotewhat are the custom header & footers ?? How can I create them & how to use them ?
Again it's in the manual and discussed on the forums. Since you have to ask these questions, you aren't ready to create them - http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#admin_theme (http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#admin_theme).