The header color is a code change - let me know which version of AbanteCart you are using and I'll give you the how-to
The four boxes under the slider banner are part for the default install, but they have been edited. They are located in a block called Main Page Promo.
Easiest way to get there is to go to Design > Layout , select home page, then click on the Main Page block to edit it. It is the standard editor functions.