how to change the header and set homepage?

Hello, 

everyone.

I'm a newer, There is a question for Moodle2.4. I know how to change the header of whole pages, but if I just want to change the header of index page, how can I do? 

Another question is how to set the index page as the first page. I hope if guests don't login, they can't see my homepage. I believe I can set that in the site admin, but I tried that, it doesn't work.

by the way, I use the theme as formal-white. 

Shan