Shopping Cart Community

I want to use two interspire shopping cart in the same web hosting account.
One use for current online sell use.
One use for testing for myself.

The shopping cart which current online sell use
locate in root directory.

The shopping cart which testing for myself
locate in a folder called newsite ...

I want to know which file I can edit to remove header and footer in checkout page?

I want to change page menu item (change some wordings and hyperlink.)
I know that page menu file locate in /_master/Snippets/PageMenu.html

In this file I also find the variable called "%%GLOBAL_PageName%%" and "%%GLOBAL_PageLink%%".
But I cannot find any information about these two variables.
I ...

But why I cannot add image in header?

I want to change the header,in my interspire shopping cart.
I changed coding in PagesMenu.html file. All of wordings and formatis success edit. But I don't know why can't I to change background and add new image in PagesMenu.html file.

Could anyone help me?