Customising

I need to customise the index page (maillist.html). Do I have to edit the 
idxpgbegin resource file. Where is this file to edit? If you have to write it 
what do you save it as? Can someone give me very simple step my step 
instructions on how to customise the index page. For instance just tell me how 
I 
can make the background white.

Any help will be much appreciated,
Michael Acheson